Cannot Edit Merged Columns' Content

If you merged pretty large number of columns (e.g. 7) and when you hover over elements of columns in Visual Composer and there are no option panels for editing, please go to Theme Options -> Other -> Additional css/html -> Your custom css code and paste the following lines:

.trx_sc_column_item { width: 49% !important; }

Save the changes. This should solve the issue.