Nation flag skinning issue

Hi, I have a strange problem with a realistic flag collection I downloaded (from elsewhere, but have since played around with its nomenclature a bit), and the program seems to leave random instances out.

I have attached two screenshots, one shows Australia, flags missing in two places on the nation screen, the second showing Bangladesh, perfectly in order. There is three folders, large, medium and small, containing 180*110, 180*110 and 25*11 size png files, named identically across the three folders, and config files set up, only to use the "large" folder files as "flags", the "medium" folder as "logos" and the "small" folder content as "icons". A good 5-10 % of nations miss their flags in the position as shown on the pictures. I am completely clueless to what is going on...

@X Y Check whether the filename extension is PNG instead of png. FM won't read them if they're in the former format.

They are all correct lower-case pngs

Its actually not that many nations
Australia
Mongolia
Northern Mariana
Palestine
Central African Republic
Sudan

Originally, there have been a few icons that have either been missing, or called a wrong name (the original author seemed to veer between Olympic shorthands and first few letters of the nation). However, in the latest version, it all should be fixed. All the mentioned nations above should be set up completely identically to the others. It also does not appear to be a missing file case for me, as the the large and medium folders are identical (save for config file word change) and the small folder has been also generated by an algorithm...

Check whether the UID is replicated in each config file more than once, and have only the one with the correct path. For example, the Australia line is in both the Asia and Oceania sections of the config, despite the graphic only being in the Asia section.

Yes, it seems the original author was less careful with his setup than what I have already discovered. I think I will just recreate the whole thing as some flags (especially icons) could have a nicer compression with a conversion from an svg file. This would also allow for an introduction of a larger size than 180x110. What would be a practicable larger size, for the "flag" folder?