unacknowledged OK-Prompt via OAR appears again after Restart, if Phase got failure/Hold in between

We have following situation:

During an unacknowledged OK-Prompt send via OAR from a phase via REQUEST=3401 can occur any Hold from the recipe. After restart these prompt seems not really be cancelled with the REQUEST=6000, because it appears again but without any message. Further other prompts function normal.  System is DeltaV12

Could trace also a REQUEST=10 for some seconds as answer which should be an error code.

1) I couldn't find any description of the number 10, or even any other.

2) how can we cancel via a special request to BEX such old message

3) Is there a possibility to do the failure acknowledge from a piece of code instead only the click on the failure button in the BOI? In the new BOI graphics this control buttons are combined in an active-x and no VBA code is visible behind this button

Thank You and Best Regards