@MVE, it’s not completely clear what you might have meant when you said you “replaced the .APP file in the Applications Folder.” I’m casting no aspersions on your computer skills, but people on the forum say all kinds of imprecise things, so one never knows. You shouldn’t be “replacing” anything, as in getting rid of one thing and substituting another.
Try an update following the instructions in this guide exactly:
https://forum.manager.io/t/installing-or-updating-desktop-edition-on-macos/7116
Don’t uninstall anything first. Of course, if you already did exactly that and are up to v16.12.0, no need to do it again. Some Mac users are experiencing this problem, but most have been cured by an update.
By the way, Manager is frequently updated several times per day. Of course, most updates are not noticeable to most users. Only major functional changes are announced.