Describe the bug
Created a WeakAura that displays a frame on top of a group/raid member when they write "123" in group or raid chat.
Summon Group
Due to the nature of the WeakAura being used outside of combat the raidcomposition can change while states are active. Due to this i am also tracking the event "GROUP_ROSTER_UPDATE" and change the state to include the updated unitId. Due to the implementation of LibGetFrame the library has not yet scanned the new unitIds and frames when WeakAuras wants to update the frames. I have to manually delay the code that i want to run on "GROUP_ROSTER_UPDATE" to wait for the new frames to be stored properly by the lib.

Do you have an error log of what happened?
no
To Reproduce

1. Import the WeakAura i linked
2. Edit the trigger to run the code of the delayed event "WA_RAIDFRAMES_UPDATE" on "GROUP_ROSTER_UPDATE" instead
3. Form Raidgroup
4. Drag group members around

Screenshots
https://streamable.com/eu437

Did you try having WeakAuras as the only enabled addon and everything else (especially something like ElvUI) disabled?
Yes

Which version of WeakAuras are you using?
2.15.4

Was it working in a previous version? If yes, which was the last good one?
I started making this WeakAura on the current version of WA

Additional context
A suggestion was to add a callback to LibGetFrame once the new frames are cached to solve this issue.

The way you do it with a delay after GROUP_ROSTER_UPDATE is correct.
There is no generic way to know which of your code or is executed first on the event, without a delay your unitframe addon may not have updated it's frames yet.