Hi @lumberjacklurch,
Could you please share a bit more about the Managers column in your SP list?
I suppose that the Managers column that you mentioned is a Person type column in your SP list, is it true?
Based on the formula that you provided, I think there is something wrong with it. The LookUp function could only be used to find the first record in a table that satisfies a formula.
If you want to retrieve the department ID for each one of the extracted records, please take a try with the following workaround:
Set the OnSelect property of the "Collect" button control to following:
Set(var_CurrentUserEmail,User().Email);
ClearCollect(
col_CurrentUserDeptIDs,
Filter('20181119_case13',Manager.Email = var_CurrentUserEmail).ID
)
On your side, you should type following:
Set(var_CurrentUserEmail, Office365Users.MyProfileV2().mail);
ClearCollect(
col_CurrentUserDeptIDs,
Filter('YourSPList',Managers.Email = var_CurrentUserEmail).ID
)
The col_CurrentUserDeptIDs collection as below:

Above formula may cause a Delegation issue, in order to get rid of this issue, please take a try with the following workaround:
Set the OnVisible property of the first screen of your app to following:
ClearCollect(RecordsCollection, 'YourSPlist')
Set the OnSelect property of the "Collect" button to following:
Set(var_CurrentUserEmail, Office365Users.MyProfileV2().mail);
ClearCollect(
col_CurrentUserDeptIDs,
Filter(RecordsCollection, Managers.Email=var_CurrentUserEmail).ID
)
Best regards,
Kris