iMovie 10.1.13 upgraded uninstalled 2x. Start to edit movie, then tools break into colored blocks on screen and not responsive,

To repeat my earlier suggestion, I would call Apple Support. I have never before seen the issue that is displayed on your screen shot, so I am thinking that it might be related to the recent upgrades and updates.

Since you already have tried a reinstall of iMovie, you could try a few other diagnostic procedures:

1. Try opening iMovie while holding down only the Option key, and selecting to creating a new library in which to open. See if the problem replicates in the new library.
2. Try booting up in Safe Mode and, after everything loads, reboot in normal mode. Now see if iMovie functions properly.
3. Try opening iMovie in a new or different user account. You can create a new user account from System Preferences/Users and Groups.

-- Rich

I HAVE A SOLUTION!

It took me nearly two hours with Apple Support to get to the bottom of it, but here's what ended up working (it's a weird fix...the Apple Pro said it was the weirdest fix that he'd seen(!)):

Open System Preferences > Accessibility > Display

If "Reduce Transparency" is checked, uncheck it.

That fixed it for me...hopefully it'll work for y'all, too!

I can confirm that using Time Machine to go back to iMovie 10.1.12 fixes the issue. I also had to restore my older iMovie libraries since those were no longer compatible with 10.1.12 version.

Be sure to turn off auto updates on your Mac (System Preferences->Software Update), otherwise it will just re-apply the 10.1.13 update... Sure hope Apple fixes this soon!

Restoring from Time Machine replacing iMovie 10.1.13 with 10.1.12 (and also restoring all iMovie Libraries opened with the buggy

iMovie 10.1.13) solves the problem on my system (10.14.6, Mojave). So the culprit is the 10.1.13 iMovie app.

So Apple should soon provide a patch!

This appears to be similar to a problem with the latest version of FCPX.

The solution on the FCPX forum is this......

Go to System Preferences->Accessibility->Display and turn off both reduce transparency and increase contrast.

Might be worth checking what the settings are.

Thanks for this. After reverting to 10.1.12, I was faced with reinstating the older database. Then I saw your solution for FCPX. I turned off the 'Reduce Transparency' setting, reinstated 10.1.13, and so far so good. Thank You.

Try going to System Preferences>Accessibility>Display. Check your settings there. If the boxes that say "reduce transparency" and "increase contrast" are checked, then uncheck both of them. Thesurreyfriends who post here mentioned that FCPX had a similar problem and that solution worked for FCPX. If it solves it for you, post back if you have time, as it may help others with the same issue.

Good luck with this.

— Rich

I can confirm this workaround solves the issue with the unreadable menu's in iMovie 10.1.13.

In my case only the "Reduce transparancy" was checked. Unchecking that did the trick.

I do recheck it after the iMovie session though - Dark Mode looks a lot nicer with "Reduce transparancy" on...

Try opening iMovie while holding down the Option and Command keys and selecting to delete preferences in the box that appears. iMovie will open in a new library. Reopen your old library to get back to your projects. Now see if version 10.1.13 works properly.

-- Rich

Try restoring your iMovie library from your Time Machine backup to a date just before you did the update. You will lose whatever work you had done following the update.

-- Rich

iMovie 10.1.13 has just been released and there may be some glitches until they get worked out. I suggest that you click on the "Contact Support" item in the upper right hand corner of this forum's screen. Follow the screens to navigate to iMovie. You should find a telephone number there to call Apple Support. Those folks are pretty knowledgeable and you may be able to get some guidance there.

-- Rich

YES! That seems to resolve the problem when using VLC for playback of videos. Switching either back on makes the problem return. Not going to risk trying to run iMovie though as too many projects could be lost again, but seems to be the answer.

Guess you can/could turn this off when wanting to use any program affected by this bug.

This all makes sense now with the colors flashing on MENUS which the 'Preferences->Accessibility->Display' setting affects, of course.

Just reporting that I had the same problem as other users. Fortunately I have Time Machine so I was able to revert to version 10.1.12 and restore my previous library. It seems unfortunately common these days that "updates" create more problems than they fix.