I can't consistently reproduce this bug. I did notice that on my "other levels" NXP (not quite the same as my Recycle Bin one; this one contains levels that are perfectly viable but just aren't currently in any pack, for example, my NeoLemmix Community Pack contributions and contest entries), I'd sometimes get this issue on "The Longest Minute" if it wasn't the first level played, but this doesn't always happen.
Nonetheless, I've made a change to the code that should fix this. But given that I don't know a consistent way to trigger this bug, I can't say for sure if it's fixed.