Actionmessage not working on paper build 473 and newer

Summary

Hello. actionmessage mechanic is broken on newer paper builds, specifically 1.16.5 build 473 and newer. It causes actionbar message to appear blank regardless of what you put in the m= field, overwriting any other action bar messages previously displayed from other sources.

Steps to reproduce

1. Get this mob on your server with paper build 473 or newer

ActionMan:
  Type: ZOMBIE
  Skills:
  - actionmessage{m="Action message! You must be on older builds!"} @PIR{r=30} ~onTimer:10

2. In accessibility settings, change Text Background from Chat to everywhere to see the issue more clearly
3. Spawn in the mob and see the issue.
4. downgrade to 472 and repeat the above

Current behavior

Actionmessage sends blank message

Intended correct behavior

Actionmessage sends the correct message