By testing Seblod version 3.8.3  and Joomla 3.5.1   I found a malfunction.
	All my forms that contained a test user ID field filled dynamically no longer worked.
	After checking I located the problem with the file \ plugins \ cck_field_live \ joomla_user \ joomla_user.php
	
	When selected the User id field the variable returned is of the type 'integer'.
if ( is_array( $live ) ) {
             if ( $excluded != '' ) {
               $excluded   =   explode( ',', $excluded );
               $live     =   array_diff( $live, $excluded );
             }
             if ( empty( $live ) ) {
               $live   =   $default;
             } else {
               $live   =   implode( ',', $live );   
             }
           } elseif ( $live == '' ) {
             $live   =   $default;
           }
 In the loop
elseif ( $live == '' ) line 82 this causes an error of choice.
 We must therefore change the test elseif ( $live === '' ) and then everything is ok.
I hope this helps you.