Any email that i use categorise or mark in say inbox,sent,del etc causes it to show no msgs in folder

In version 7.0.26787 emclient, if i select inbox say and then select a msg, then click categorise from the toolbar, and then go to say sentbox and then back to inbox, all the messages disappear and then there is just a spinning object in the center of the inbox window. This happens also with the mark button. This problem also happens in sent,deleted,trash etc. There is no way to fix this other than remove the account and re add it again. Also possibly as well right clicking and selecting categorise or mark also does this. please fix this thx.