HomeKit not retaining code-based guest access permissions

I have Apple TVs (4K, connected via Ethernet to Internet) in two properties, and experiencing the same issue. I’m using Aqara U50 smart locks, and have guests set up with access codes (so not Apple IDs) and the permissions for these accounts seem to reset on almost a daily basis. It doesn’t make any difference if I remove the access and re-add, or create a new account.

I have read in the Apple Forums that others have been similarly affected and they were using Schlage smart locks, so it doesn’t seem to be the locks that are the issue.

Could it be that HomeKit is treating the access as one-time only, and resetting the access once used? If so, this is a bug as there is no option to set the schedule / time for guest access.