@Robert94
Try these steps: A, B or both, below:
If neither work, try C. at the very bottom of this post.
A. If you recently added this column RowNumber, try a data source refresh like this:
- Click on the database looking icon on the left side

- Identify your SharePoint List data source, and to the right, notice the ellipses. Click on these ellipses.
- In the menu, click Refresh

See if it helps.
B. Does adding
Refresh(S2T1_meetingActions)
after the With help?
With
(
{c:colMeetingActions}
,Patch
(
S2T1_meetingActions
,c
,ForAll
(
Sequence(CountRows(c)) As myIndexNo
,{RowNumber:myIndexNo.Value}
)
)
);
Refresh(S2T1_meetingActions)
If the above formula helps, performing the data source refresh with the ellipses steps above in A. should no longer be necessary.
Using the Refresh(yourDataSourceName) is, however, not a substitute for the ellipses steps. You do need to do the ellipses steps in A. again though each time you add or modify any additional columns in the data source, so they can be recognized for use in Power Apps Canvas App formulas.
C. What is the Items property of your Gallery?
If it is currently set to a variable or Collection, it's because this variable or Collection is not being updated that you observe this behavior. In that event, consider to use the Data source directly instead for the Items property of your Gallery.
If you absolutely must use the variable or Collection, then you could consider this as a possible solution: check out how you're currently building the appropriate Collection or variable now before you're feeding it into the Patch, and just rebuild that Collection again or set that variable again in the same way right after the Patch so that it has the updated records after the Patch, and this will cause the Variable or Collection that the Items property of your Gallery to now have the updated values and this way the Gallery should be updated now.
See if any of the above help @Robert94