Actually, upon further inspection the issue seems to happen before saving.
Steps to repeat:
– Create a form with 50 conditional rules
– Switch to form editor, edit something
– Switch back to conditional rules, all rules are empty
So something is happening to my rules when I edit the form itself, without even needing to click the save button.
I know there is some JavaScript event attached to the form editor, because if I change the name of a conditional group in the form and switch back to the rule editor, that rule has been reset. Whatever code is doing that also seems to reset the rules if there are 50 conditional rules and you edit the form.
It’s a known bug, but there’s an easy workaround: add 51 conditions.
https://github.com/pwkip/contact-form-7-conditional-fields/issues/109
That solves my problem! Thanks for your help.