String translations changes not getting saved, form reset

Hi. it seems the changes in my string translation are not being saved. After hitting the ‘save changes’ button, the form is being reset to default. Any thoughts on this would be appreciated.

Setup and tried:
– Newest WordPress and Polylang versions
– LZ One page theme, but same happens with default theme
– All plugins deactivated, makes no difference
– I tried clearing browser cache
– I tried the previous 2.6 version of Polylang, same behaviour
– I tried custom registered strings, but removed them to default to keep testing; no difference
– I cleaned the string translation database; same behaviour

I’m out of options now. Thanks for your help!