Hey @Acorn50, we currently have this issue in progress: Refactor autonumber fields to use transactional counters by dimmur-brw · Pull Request #5238 · baserow/baserow · GitHub. I assume it could be related to your issue.
Hello,
Quick update here, i was having the problem even on tables where no API was connected, like @Acorn50 described.
I have a workaround on the table for which i really need a sequential numbering with no gaps where the numbering is done in a make scenario.