I very much doubt worth fixing, but an oddity. Here's an illustration (latest macOS, latest Verbum):
1. I'm on Desktop 2, with Verbum open. In a resource (here, NT Apocrypha), I do a simple text find (Cmd-F):

2. I switch over to Desktop 1 (a blue-sky background; I use for Safari, etc):

I tried various 'versions' just to see what the principle is. Probably I'm wrong, but it appears the Find-Text box, at least on the Mac, is attached to Safari (which here, uses Desktop 1). With the find-text box open, the desktop management keeps trying to switch Verbum (desktop 2) to desktop 1 (losing Verbum of course).
Workaround: close the find-text box after use!