It appears ja-mashead 1.2.0 has an error on the backend. Module still showing on front end ok.
An error has occurred. 0 implode(): Argument #1 ($array) must be of type array, string given
You can try this solution:
https://www.joomlart.com/forums/d/50544-php-error-after-upgrade-to-520/4
saguaros thanks!