my invoice numbering has suddenly changed - it now seems to be using the same number followed by random letter or letters. Why is this?
Have you changed any of them at all? It will pick up on your last invoice (even if its draft) and carry on from there.
May just be worth checking over your last few to see what’s happened.
I see a few invoices there that are suffixed with ‘R’. It’s best to avoid suffixing any letters as it can confuse the auto-numbering system, it will try to iterate alphabetically from there on.
to correct this just go to your last raised invoice and update the invoice number to contain exclusively numbers (or letters at the beginning are fine). After that the numbering will pickup from there.