Ah, so that's why the new skills disappeared when I started the level.
Well, anyway, thanks for the fix - as you can tell by me having updated my levels, it works for me now.
One question though: How can we make other styles work with the newest experimental build, now that you said the tileset restrictions are no longer in place?
I tried copying over my styles folder from my 12.11 folder, but I'm getting an "invalid pointer operation" as soon as I want to playtest a level (even when using the official styles).
I've deleted the copied styles folder and extracted the one from the latest experimental build back into the folder again, i.e. the one that only includes the official Lemmings and ONML styles, and now it works again as previously - that implies the restriction to official tilesets might still be in place somehow?