Hi @Michael1 ,

I would do the following:

The lookup field would be a Rollup and set to get the AVERAGE(values)

Then in the formula field I would do something like this

DATETIME_FORMAT(DATETIME_PARSE({Numbers},‘hh:mm’),‘hh:mm’)

Or if you want to keep it as a LookUp field you can put the formula like that
DATETIME_FORMAT(DATETIME_PARSE(AVERAGE({Numbers}),‘hh:mm’),‘hh:mm’)

Hope this helps

Thanks that helped!
I just had problems with NaN fields and ERROR after that, but I just combined ISERROR with your formula.

IF(ISERROR(AVERAGE({Numbers}))=0, DATETIME_FORMAT(DATETIME_PARSE({Numbers},‘hh:mm’),‘hh:mm’,BLANK()))

I may be boring,
But do you know why does it show me numbers that are ending with “0” like this

Formulas I used:
Lookup Numbers > AVERAGE(values)
test 0316 > IF(ISERROR(AVERAGE({Lookup Numbers}))=0, DATETIME_FORMAT(DATETIME_PARSE({Lookup Numbers},‘hh:mm’),‘hh:mm’,BLANK()))

Had to use ISERROR because of error and NaN.