As far as I can tell, all of my fields are still intact, but it looks like most of the Custom HTML has been stripped out. This is where all the info and instructions for the forms were, so hoping I can retrieve that somehow.
I'm not sure if this is relevant, as it applies to the submitted content, not the forms themselves, but when I updated to version 2.2.2, the Custom Fields in post tick box (under User Frontend/Settings – General Options tag) defaulted back to not show custom fields on post content area.
So I had to tick that box again to restore the missing content.
The content from the missing fields – including most recent – are nowhere to be found in the database. I was able to retrieve the content from a database backup. But don't feel confident that Custom HTML fields are “safe” to use.