I set up AIP policies and labels last year for our company to use foe email labelling and document labelling. We were also using the advanced feature to show a warning pop-up message when sending emails to externals. This has been working for months but suddenly stopped working. The AIP add-in is nolonger there incl in disabled adds.
How does the configuration look in Azure? Or have you migrated your labels to the M365 portal? If all settings are OK and you haven't configured anything that could cause this, you need to create a support ticket with Microsoft. I've previously heard of similar issues so it can happen.
