Something seems to be off regarding the automatic number generation. It seems like deleted clients are not really deleted but in some kind of recycle bin. This is a fresh V5 installation with a csv import of 17 clients that were deleted afterwards.
Even after removing every client, going back to default settings by remove the “K” in front of the counter, the problem still persists. I cant generate a client with the numbers 1-17 and 19-21 for some reason.