Sales orders not saving, can't be submitted

I’m self hosting ERPNext v14, and I’m facing a strange issue where I’m not able to submit some sales orders - the status shows Not saved, however upon clicking Save I get a notification showing it’s been saved. Because of this I can’t submit the SO. This issue doesn’t occur for all customers, only some - the affected customers I could submit for successfully before. The Console doesn’t show any errors, nor do the logs

Problem was with the Frepple integration, removing it fixed the problem