The paintbrushes stopped working

Two days ago, when I opened the app, all the brushes I had added from the "Discover" section had disappeared. I'd been using them for months and this had never happened before. I thought it would be fixed simply by reinstalling them, but I've been waiting for two days and they haven't installed. It just says "Adding..." but no matter how long I wait, no brush pack installs. The default brushes work, although sometimes the brush names disappear and only the sample line appears. I don't know what happened, and I don't want to uninstall and reinstall the app because I'm afraid my work will be lost. What should I do? (I have the Windows PC version)