I can confirm that this is a maxvars issue. I have a repeater with just over 50 various fields. Adding additional fields outside of the repeater worked fine. Adding an additional field within the repeater caused some of the repeaters settings to revert.
For example the repeater layout reverted from “Rows” to “Table” and the button label reverted from my custom string to “Add Row” and I couldn’t save my desired settings unless I deleted one of the repeater subfields.
For those who stumble across this, I simply overrode PHP’s max_input_vars default (1000 I believe) in php.ini. 3000 did the trick for me.
