Remove all other CC and mods into a temporary folder outside the Sims 4 folder. The best way to verify that the problem is happening due to MCCC and not other mods/cc is to run the game with only MCCC in the mod folder.These LastExceptions will continue to happen until the mods/cc causing problems are removed or updated. Note that I did include CC with that! Some of EA’s patches breaks custom objects or clothing items as well and sometimes it can prevent mods from working correctly if they are deployed. These almost always happen as a result of bad or out-of-date mods or CC.
This VERY OFTEN has to do with other mods/cc that are out-of-date and are preventing the rest of the mods from loading due to their errors. You can tell this happened by going to your Sims 4 folder and you will see a LastExceptions.txt file that is generated during game loading. If this happens, you will not see MCCC in the game even if you have it installed correctly.