Never used the Micro Mark stuff, so I cant offer any help there.
I use Ambroid or Bob Diveley as I have both.
is it really thin and runny? or is the problem something else? With out knowing exactly what the problem is or not having used that product before....
Try this, Put one coat of masking on....allow to dry thouroughly(I know the brands I use can take from 45 minutes to several hrs depending on how thick the coat is) After it has dried put on another coat really concentrating on the areas which have given you problems....
Micro marks masking may require several coats to build up full coverage and protection, like I said I havent used it before. With the Diveley and Ambroid one coat is all I need.... Also are you thinning it any? If so you might want to try it without thinning it at all.....
Hope this helps