If you hear the striker engaging, then you don't have the classic gremlin. If you pull the trigger and hear a click but no bang, it could be a few things. The striker may not be fully engaging due to obstruction or a weak striker spring. It could be the firing pin. You said you cleaned the rifle. Does the firing pin rattle freely when you shake the bolt? If not, there could be some crud in there that hangs up the pin intermittently. It could also be the ammo. It's not unheard of to have ammo fail to fire the first time and then go off the second try. I recently had a batch of Red Army that had some duds in it. My duds, however, were heavily dimpled.
Converting the FCG from full-auto to semi-auto is what produces the Gremlin. The first company that did the conversions was aware of the problem and did add the tab, and so did other companies following, but the first company then patented the tabbing and prevented anyone else from using it. The lack of a tab on the VZ 2008 is not a stupid design, but instead the result of legal obstruction. Sending the carrier in to be tabbed is consistent with the original design of the semi-auto VZ.
The VZ 2008 is an excellent firearm with numerous advantages. It would be a shame to write it off. As they're made with used parts, however, there may be some with quirks. Overall, it's a simple design. Fixes are usually cheap and/or easy. Go to www. czfirearms.us for a ton of trouble-shooting and repair information.
But... if you don't want the aggravation, you could always sell it. I'm sure you'd easily find a buyer.