I can't get two slurred/tied piano chords to play together

Hi. I am brand new to Musescore, and and delighted to discover it. Thank you to everyone who has labored to make and support it.

I am a gross amateur regarding music notation so forgive me if I have made some foolish error here. I just tested something out in Musescore and it does not seem to be working. I just created two simple 3-note chords using a piano instrument sound. Both chords are whole notes in 4/4 time and I connected them across the measure bar with a tie so that the player will play the first chord and hold it across the measure into the 2nd chord (simulating the sustain pedal).

Unfortunately, even though the tie is clearly visible on the screen, the program's music player plays the first chord, stops the sound, then plays the 2nd identical chord. No sustain effect occurs. I've tried changing the instrument to strings and the same thing occurs. I tried changing one of the notes so that the tie becomes a slur, and still the player plays two very distinct chords with no hold between them. I've also changed to four chords in a measure using 1/4 notes, but still the slur/tie does not work.

What am I doing wrong? How do I get the program player to hold down notes as it plays to simulate the sustain pedal or a continuous string bow?

Thanks in advance for your help!

Frank