Critical bug in Episerver/Optimizely Forms 4.30.1/4.30.2 - upgrade ASAP!
Episerver Forms submission data older than 30 days can be unexpectedly deleted, even if the form is configured to keep submissions forever. If you are using version 4.30.1 or 4.30.2 - I would recommend upgrading ASAP to prevent loss of data. The issue is fixed in 4.30.3.
Read the release notes: