can you copy and paste in this discussion the condition expression you are using in your sheet properties to verify if user can view the sheet?
I suspect that by hitting the clear button you are clearing the user and so on teh conditional check it's coming back false so not showing you the sheet?
Problem resolved - thanks for pointing me in the right direction
I also had a trigger on opening of the document which selected the user from the same spreadsheet.
seems like the load trigger is cleared when selecting the clear button.
I just added the on username trigger back into the clear button after the clear action and it works ok.
(not sure if this is the most elegant solution but it works)
On load trigger
Conditional - show sheet
sum(Dashboard) = 1
Excel sheet contains
FROM [60_DataSources\Security.xlsx] (ooxml, embedded labels, table is Sheet1);
If the username you have mentioned is the in your section access then you can tick the 'Initial Data Reduction Based on Section Access' option on the 'Opening' tab of 'Document Properties'.
This will reduce your username field to one user - the currently logged on user - so there will be no need to select it.