Automatic synch when changing audio source for a MS score is not working

Hi there. I have published 100+ songs with vocals (VOCALOID5) on MuseScore and it has always been easy. Export MS-score as a .wav file, add title image and save as .mp4 video file. Upload to YouTube. On MuseScore open score, select options and Audio Source, enter YouTube link, click on save, check 'Video by default' and 'Audio only' and then click on the button on the far right-hand side to get the SCORE AND THE VIDEO TO SYNCH AUTOMATICALLY AND PERFECTLY. This synch button has disappeared!! Happened about 4-5 weeks ago.

Of course one can as a workaround use "M" to enter markers for the start of each measure, and even drag them backward and forward to get a perfect match but that is very time-consuming.

Surely this cannot just be me? Is anybody else having this problem? Is the bug know to MuseScore? When may we expect a fix?

BTW: thanks to Marc and the whole MuseScore-team - this incredibly complex but intuitive and easy to use programme has changed my (musical) life. It makes composing and sharing music just so easy and so much fun and is worth its weight in gold. CONGRATULATIONS to the whole team.