Hello again,
we had the opportunity to check with debug, and the error is the following:
Deprecated: strstr(): Passing null to parameter #1 ($haystack) of type string is deprecated in [ojs_app]/cache/t_compile/2122dd4b4d038d06701b7a5cbc73d21546ea835d_0.app.formtextInput.tpl.php on line 141
Deprecated: strstr(): Passing null to parameter #1 ($haystack) of type string is deprecated in [ojs_app]/cache/t_compile/2122dd4b4d038d06701b7a5cbc73d21546ea835d_0.app.formtextInput.tpl.php on line 126
Maybe the plugin has to be updated for OJS 3.3.0-13?
Many thanx
P.S. it seems also that another user has a similar problem