Steam version. Edited an existing ship, saved it, uploaded to workshop, no problem. Edited a second ship, saved it, uploaded to workshop and I get no error but the ship has vanished without a trace, does not appear in any deployment screens. A few minutes later, I restart GSB, and the ship is back. Perhaps workshop upload related?
I just ran into it again, this time editing an existing ship and saving it (but not submitting it to the Workshop). The ship disappeared from the deployment list until I restarted GSB2.