I have set up a view (modern experience) on a list in a SharePoint Online site, grouping by a 'Meeting Date' column and sorting on a 'Time' column (ascending order) then 'Requirement' column (ascending order).
I and other users are seeing incorrect items being placed into each grouping, and items being sorted in the wrong order within each group. There is no apparent pattern to the order (i.e. it is not falling back to a sort on 'ID' or other columns).
'Meeting Date' is a Calculated Column, which looks up a 'Meeting' (Date & Time) column and returns as Date only. 'Time' is also a Calculated Column, which extracts the time from the 'Meeting' column and returns as Text. Finally, 'Requirement' is a Lookup column returned as Text.
I have kept all other view settings as close to the SharePoint defaults as possible. Is there anything I have missed which may be causing the items to appear in the wrong order, or could this be a SharePoint bug?