How to get Final Cut 10.4.2 working after installing and then deleting 10.4.6 trial version?

So I 100% need this particular Macbook to stay on Mojave and had been using Final Cut 10.4.2 without issue. Then I found an installer I'd saved for the trial of Final Cut 10.4.6 and installed it, leaving two versions of FCP on the computer. For reasons too boring to explain, after a day, I decided to delete the trial of 10.4.6 and just stick with 10.4.2, but suddenly that has become unusable. Whenever I click on "import media", even with a brand new project, the app crashes. Any ideas on how I can get 10.4.2 working again?

Thanks in advance for your help, and even if you see that someone else has answered this, please know that I'd appreciate your input, as well.