I've been trawling the php error_log, chances are I fixed it between your original post and my reply.
Quite a percentage of code required work when moving to PHP 7, some deprecated functions and some things that were already iffy under PHP 5 broke in 7, including some return by reference code that isn't handled the same way anymore. I've been chasing this for a few days but mostly everything should work at this stage.
_________________ --- Sibbi
Disclaimer: The opinions stated do not neccesarily represent those of my employer.