Hello,
I had 2 contacts on my page and i made 2 different catagory for mail-custom-fields and made also different custom field for each catagory and contact it was everything ok on joomla 3.8.3 after update to joomla 3.8.5 and more the custom field appear on all of contacts and not just on selected field categories.
i tried to use a new instal joomla but it has the same problem i hope you can to help me to solve this issue .
thank you
regards
N.K