Quote/Order/Invoice numbering issues

Hi, 

Since we turned on the different number sequences for quotes, orders and invoices, the warning for duplicate invoice numbers no longer works. I've been told this is a known bug.

However, we've also noticed that when converting orders to invoices, the number doesn't change to the correct sequence, it's keeping the order number (even with the preference set correctly). I've cleared cache as suggested by support but it's happening on multiple computers with multiple users so I think it's another bug. 

The *helpful (please read sarcasm) workaround offered was to change the number manually. As if we have time to try and find what the last invoice number was whenever we change an order to an invoce - with multiple users, and not every invoice being created from an order!

I thought maybe it was because we used a # on the front of the order number sequence. I'm sure I got that idea from a post somewhere announcing that this feature had been added but the help pages don't show it. So I just went to change the settings to a letter prefix instead, lo and behold, the number sequence somehow changed on Friday and had reverted to running the same numbers as our invoices. They're not changing either so it wasn't the # causing the issue. (Maybe editing an earlier order overrode the sequence I'd set????)

I've just tried this with a test order and invoice with a letter prefix for the order number. It still didn't work.

Has anyone else experienced this or found a better workaround?

PS. I don't consider "use the browser" to be a workaround so please don't suggest it. Too many features we use are not available there, like categories on sales invoices.