Lord knows what went wrong, but a number of us here including myself have had similar problems with Microscale Mico-Flat. No worries with fixing it, just hit it with a proper flat coat. I use Future floor finish mixed with Tamiya X-21 Flat Base at a ratio of 4 parts Future to 1 part Flat Base. The main caveats with Future/X-21 Flat Base is to mind your ratios, mix thoroughly, and NEVER try to spray X-21 Flat Base directly on your model without having mixed it in Future at the proper ratio.
I also have used Testor's Dullcoat, with mixed results: some bottles are flat others are more satin to semi-gloss. Polyscale makes a clear flat that I have heard many good recommendations about as well, although I've never used it myself.
Andy