My app creates a reference number for a report using the item ID of the SharePoint list, however yesterday it appears to have just stopped working and I have no idea why. I can't find any service wide bugs being reported and I've tried going back to previous publications of the app too with no luck. I'm the only one who edits the app and I hadn't worked on it since last Friday at which point it was all still working.
Screenshots to help show the problem. The red number is automatically calculated when a new report is made to ensure there is no duplication.

RefnoID:

However, report 2021-10539 has already been submitted and I have it set that an error card shows if anyone tries to submit a duplicate reference number. This error should cause the ID to refresh and update but it is not working either.
Now even though there have been multiple new reports on the list (which had to be input manually rather than through the app) these new IDs are not recognised or picked up see:

This means the reference number in the app should be picking up 551 instead of 539.
This has been working absolutely fine since it launched in January so really not sure what's changed or happened. I have tried refreshing the data connection. Is there anything else I could try?