These two problems are repeatable upon opening the app.
PROBLEM (1) - The 3-dash icon in the timeline window, upper left WILL NOT open the drop down menu when you left-click it. This is the drop down menu that allow you to Insert or Remove tracks in the timeline. RESULT - I CANNOT add or remove tracks.
PROBLEM (2) - Situation - I have a space between two video clips on a timeline track. Then when place my cursor in the space and right-click, the “remove” pop up does not appear. RESULT - the only way to close butt up the two video clips is the left-click and drag the right-most clip left toward the left-most clip.
NOTE - these two functions work perfectly well in Shotcut 64bit V20.09.27.
Do you use an extended monitor? If yes, just try to experiment by dragging the ShotCut app in your main screen then try to click the “hamburger” menu (3-dash icon) if it works then drag it back to the extended monitor and do the same. If it doesn’t work on the extended monitor then try to change the scale of either of your monitor - experiment!.
My main monitor before was 150% Layout and Scale then i changed it down to 125%. I did not change the scale in the extended one. That solves the problem for me but i really don’t know about what is your hardware setup, i mean, if you have an extended monitor. Cheers.