The NXMO file you've attached is not expected to work with NL 12.10 and onwards. There were some minor tweaks to the format in 12.7; the editor dropped support for the older format very shortly afterwards, while the player kept support up to (inclusive) 12.9.4 but dropped it from 12.10.0 onwards (except for NXLV files, which backwards compatibility for is still maintained).
In order to work, it will need the following changes (none of this is case-sensitive):
- "EXIT" -> "EFFECT EXIT"
-> "FRAMES 6" -> "$PRIMARY_ANIMATION" / "FRAMES 6" / "$END" (three lines)
In particular, I made a point of updating myself all styles that were submitted to NL's style library. Obviously, I couldn't do anything for unreleased-at-the-time styles directly, though I did release a tool that would automate the format update for everything except custom pickup skill objects. There were a few cases where - despite me making as much of a big deal as I reasonably could about pointing out that this had happened, that the downloadable copies had already been format-updated, etc - people submitted "updates" to their styles that were based off the pre-12.7 copies, and had not been updated, resulting in the styles effectively "reverting" to the old format and becoming a ticking time bomb that broke when 12.10 released - unfortunately I don't have the patience to inspect every single style submission to look for this kind of thing, but I believe most cases have been sorted out now, and at any rate, creators would notice it unless they're still running a very outdated version of NL (and there isn't much I can do about people who refuse to keep updated, short of making NL refuse to run if it detects an available update, which - especially given that update checks should be possible to disable, and that a minority but non-negligable portion of the userbase has experienced issues with it - is not a path I am willing to go down).
As far as the issue with those levels in the other topic go - they are a seperate bug, which I have gone into more detail about in that topic.
I have struck-out the issue from this topic that are already covered by your other one, or otherwise unrelated to the style manager bug. Regarding the bug in the style manager itself, that is something I'll need to do some testing / looking over the code to sort out.