there is no Dropbox (combobox) for Assign Participant after menu Assign was click?
Here is the error_log:
[26-Mar-2020 20:23:43 Asia/Jakarta] PHP Warning: Declaration of CustomBlockPlugin::getBlockContext() should be compatible with BlockPlugin::getBlockContext($contextId = NULL) in /home/xxxx/public_html/xxxx/plugins/generic/customBlockManager/CustomBlockPlugin.inc.php on line 134