@FoolBoy:
Your problem sounds similar to the one I've had with making new Studio items (with one appearing and then the rest not showing up and vice versa)- it's probably a conflicting CAB-string (see picture A). Every unity3d file needs a different one, so it's very important that when you use a copy of an existing unity3d file to immediately change one of the CAB-string variables (far as I know, all that matters is that the total number of symbols stays the same, and you can freely swap numbers for letters and vice versa).
In fact, I just checked two of your list files and they have the same CAB-string - so again, I think that must be it.
Actually, it just so happens I was looking at your List files to see if there was any conflict - I noticed you use the same 215 prefix (see picture B) for all of your item listings. Technically, that doesn't really matter - the game places clothing items based on the name of the text asset inside the list file (cf_f_shoes, cf_f_panst), but it does make it harder to find conflicting IDs using DillDoe's SlotID program.
For instance, DillDoe's fishnet bodystocking (found in dilldoe_Bodysuit.unity3d) has ID 213802. 213 is the prefix used for pantyhose. You used ID 21
5802 for your file Leggings LX1(color) (in foolboy_fasion_00.unity3d). But since your textasset file (like his) starts with cf_f_panst, both will appear in the category of pantyhoses - and then conflict, because the oh-so-important final 3 numbers (802) are the same, resulting in DillDoe's fishnet bodystocking not appearing in the list. But when I use SlotID to search for 213802, I get no conflicts.
That's why I would recommend that when you add new items to the game, to still try and use the right prefix - me, I just check the main game files or other people's mods.
Finally, I would just like to say that I love your work and am very happy to see you make things for HS, so please don't see any of the above as criticism - I was on the verge of sending you this info in a private message when I saw your question above.