Maybe a bit niche, but the Scanco software for computed tomography analysis. Cant remember what it’s called off the top of my head. It’s horribly dated and unintuitive. It does work though! My favorite was when we stopped being able to use it for several weeks, we thought it was busted. We contacted the company for help and they informed us that with a new update the numlock key toggled a “feature” that prevented editing files. No visual representation that editing was locked. Wild