The original gamecode has a bug that prevents any crosslevel triggers from working if they use spawnflag 8. This is most noticeable in the original Hexen II, where one of the prizes in the Temple of Mars doesn't appear.
You can test the bug yourself by making a small level with a button that targets a crosslevel trigger using spawnflag 8, and then a separate level with a crosslevel_target trigger attached to something like an item spawner. The spawner will never create the item. But if you use any other spawnflag number, the item spawner will work correctly.
I traced the bug down to subs.hc, which defines a constant SPAWNFLAG_ACTIVATED, with a value of 8. There is a function called InitTrigger, which deactivates the trigger if its spawnflags match this flag... but that shouldn't happen since crosslevel triggers can't be deactivated anyway. I made a lazy fix by setting the inactive property to FALSE on the trigger after calling InitTrigger. This fixes the problem with no ill side-effects, from what I can tell.