Quick answer: Unreal Iris gameplay tag replication skipping tags marked with NoCook? Cooked builds drop these from the gameplay tag registry; mark for ship.
Editor: tag 'Debug.Test' replicates. Cooked: it doesn't; receivers see empty.
Remove NoCook on shipped tags
Tag inspector > Cook Settings. Toggle off NoCook for tags used in production.
Or use a different tag registry
Ship-relevant tags in 'ProductionTags.ini'; debug tags in 'DebugTags.ini'. Per-config inclusion.
Verify cooked tag list
Cook log: lists shipped tags. Missing tags surface the bug class.
“Cook flags are per-asset. Tag config can have flags too.”
If you use gameplay tags, audit cook flags. Debug tags shouldn't ship; production tags must.