Repeats Don't Work

Did you make sure you have the play repeats button pressed on your toolbar?

if it isn't that you'd need to share a score showing the problem

I'm not sure if this is the source/same as the OP's problem, but I'm having the same problem, but only in an exceptional circumstance: the repeats are not at the beginning/end of their measures. In particular, I'm Scoring the 'etudes' in Carl Baermann's "Complete Method for Clarinet," and in #25 ("Variations"), he places repeats on the 'and of 2' (in two-four time); essentially, he has an eighth-note pickup, which he places inside the repeat, rather than outside it. MuseScore 3.1 (OS: macOS Mojave (10.14), Arch.: x86_64, MuseScore version (64-bit): 3.1.0.22425, revision: e26f7c4) lets me place open and closing repeats in these mid-bar locations, but playback does not obey these repeats--as the OP says, "the blue line just marches right over them"; I do have the play repeats button "on," and there are other, "regular" repeats (with first and second endings no less) in the same score, and those are played just fine. (And yes, I tried restarting the program: no luck.) I'm attaching an excerpt exhibiting the problem.

PS: Oh, and I recognize that there are "workarounds," and frankly, it wouldn't shatter my world if MuseScore elected not to support this feature...but it is "bad form"--or at least, it seems to me, inconsistent with the spirit of the program--to allow formal entry of such beasts and then fail to support them in playback. In other words, my opinions is that, if the developers decide that supporting playback of mid-bar repeats is not in the cards, then, perhaps arguably, you probably shouldn't support placing repeats mid-bar in the first place.

Mid-measure repeats don't play back, you'd need to split the measure for that. Not a bug, but by design.
Whether ot not that is the same problem as the OP's remains to be seen, although I doubt we'll get an answer to that, after almost 6 weeks of silence

Just loaded your example on Musescore 3 and it played the repeat for me, every time I played it. Just saying.....

Yes, of course, because I did split those measures.

"Repeat previous measure" notation always repeats the bar located exactly to the left of the repeated bar. This is fine for simple repeated bars within a score or repeats contained within a first ending. However, repeat previous measure fails to repeat the correct bar when used as the first measure within a 2nd or higher ending. Work around is easily handled....just copy the measure instead of using the repeat sign. But this used to work correctly before version 3 was recently updated. Why was it changed?

Seems you are highjacking an unrelated issue.

I had the same problem as the OP.
I was surprised "repeats didn't work", when they did work just fine in MS v2. So I was composing a bug report on this issue, but as per instructions, I checked the existing bug database first and found this thread.
As stated in answer to OP, the solution is to activate the REPEAT button on the toolbar.
Yes! That worked. Glad MS3 isn't broken.
But to new users, it ACTS BROKEN if it ignores Repeat marks that are in the score.
Please consider activating the REPEAT button by default when MuseScore3 is installed, so it will play properly for new users. Alternatively, whenever MuseScore opens a score that has repeats, and the button is not pressed, popup a dialog saying:
"To play this score as written (with repeats), be sure to activate the repeat button on the toolbar"
[ ] Don't show this again [OK]

Or something that gives just-in-time help.
Thanks for a wonderful program! So very helpful.

OP never came back with the requeted info, nobod else showed that there really is a bug, so let's close this

Hi Jojo,
Quite curious to understand how allowing repeat sign to be positionned mid measure and not playing them can be called "by design"?

Repeats do repeat measures, as per it's property "play countn, voltas span measures. Jumps jump to/from measures. So the entire repeats infrastructure is based on measures.

There are times when people want a repeat sign in only some staves. If the barline is dragged to the middle of a measure, it will not affect playback but it will appear there. Playback won't work, but the score will look correct. This give the user max flexibility in using repeat (or other) barlines.

"Quite curious to understand how allowing repeat sign to be positionned mid measure and not playing them can be called 'by design'?"

+1 (I agree.)

"So the entire repeats infrastructure is based on measures."

I see you elaborated to better address frfancha's post. Well, I guess it turned out that that design choice was rather short-sighted; time for a re-factor.

I know I said before that I'm relatively indifferent as to whether or not this issue is "fixed," but the more I think about it, the less indifferent I become. I'm increasingly of the opinion that if MS enables you to score it, then playback should be able to play it back (and if playback can't play it back, then MS shouldn't enable you to score it).

Perhaps there's an underlying feeling that this isn't really an issue because "when would it ever really come up"? Accordingly, I'm attaching several photos of published, classic "standard" works (in the clarinet literature, if that matters) employing mid-bar repeats: yes, it really does "come up." It would be nice if MS supported it fully, i.e., in playback, not just visually, without workarounds.

This issue here is about something entirely different though.
And issues are not the place for discussions either, that's what the forum is for.
And splitting measures is easy enough to do, so there is no need at all to redesign this. Splitting measures is not the workaround but the fix here.
From images is it impossible to tell whether these measures have been split or not. They don't playback either...

What actually is a bug though is that Ctrl+drag a barline splits the measure, but doesn't keep the repeats barline, so requires a 2nd step. Not sure it has been entered into the issue tracker yet.

Oh. so THAT'S what that button does lol

I didn't see it until now. Thank you!