Playback issues in Studio 4.3.1

I'm finding some playback inconsistencies in Studio 4.3.1 vs 4.3.0 that don't make sense - checking here before looking to open an issue on GitHub.

I have at least 2 scores where playback of some instruments isn't right when rendering in 4.3.1, but it sounds OK when using 4.3.0. The cleanest example is attached (please be kind if commenting on the actual arrangement), and I have attached a video (compressed to zip to allow uploading) that shows the problem I am seeing. In short, volumes aren't consistent note to note, and in the example below, playback of whole notes "sputters" in and out.

The issue also seems to somehow be related to the length of and other parts in the score. If I delete measures preceding this section, I still see playback problems in 4.3.1 but they manifest differently (this is the "fragment" section of the video). If I delete other parts and only keep strings, playback in 4.3.1 sounds OK.

For reference, I first saw the problem with my installed version of 4.3.1. I've since downloaded the portable version of 4.3.1 and see the same issue there (that's what was used for the video). The 4.3.0 version (where playback is OK) is also using the portable version. I'm seeing this on Win 11, using the release channel of MuseHub. Muse Sampler is at version 0.6.3.196.

I looked quickly but don't see anything like this currently listed on GitHub. Does this sound familiar to anyone?

Thanks -