Hanging large TV and media cabinet on cement block covered with drywall
The walls of standard 8" concrete block is only about 1-1/4" thick, which is not much depth for embedment for expansion type anchors.  For this reason I think it's safer to use a toggle of some kind in block.  

I find this type of toggle is easiest to use and will work fine even with drywall and hat track on top of the block:  



The one in the picture is branded "Snaptoggle" but there are many brands.  

Although 1/4" toggles would probably have enough strength to mount the bracket right on the block, I'd bump up to 3/8" toggles to compensate for the gap.