I have several custom buildings for Cities Skylines but in the "Content Manager", in the "Assets" tab it doe not shows all the assets that I owned. Is there a problem with my game or the assets itself ?
Depends. Are these assets you created yourself or that you downloaded from steam? If the latter, I would say that steam has been plagued with congestion due to the game's nodding popularity it it may just take a bit longer after you subscribe. Also, when subscribing, make sure that the you have the check mark on the assets's picture AFTER you back out of its description page on steam. Had an issue where I was hitting subscribe on the description page but wasn't registering immediately when I backed out.