I have a problem with a toilet that occasionlly gets clogged. It does not appear due to material and solid wastes. When i use a plungler to clear the clog i dont see any solid wastes breaking apart. I dont have problems with other drains in this bathroom. I have noticed that if the flush handle is quckly released the flapper does not stay up and does completely flush.

Could the problem be more to do with the flushing mechanism rather than a drain problem? Any suggestions ot tips are greatly appreciated.

thank you