No orders generated

I am having an issue where some of the orders aren't coming in, even though payments are received. They aren't under missing orders or any other order status, and I can't find anything they have in common. Some are paid through Paypal, some through authorize.net. Most of them are at least sending confirmation emails so we can figure out what was ordered. For the most part, the ones that are missing have an order number about 200 higher than the rest, e.g. 60900 instead of the rest around 60700.
I've even tried looking in the database, no luck there either.
OC Version 2.3.0.2

Update:
Every order that doesn't appear in the backend/database is in the 60900 range. The working orders are numbering sequentially, and are now in the 60800 range. I don't know why these ones are jumping out of sequence, but it seems like that is related.

thanks for your help