Time field is empty text in pivot chart report

Time field is empty text in pivot chart report

Hello all,

I am currently trying to create a pivot chart, where the y-axis is supposed to be a total sum of time. The problem Im facing however is actually using the field, where my metric is stored. It shows up as a simple time field in the form builder. In the report builder however it turns to text which it self seems to be empty. Trying to use the field simply returns "Unknown".

Ive tried regenerating the data and looking up my problem. Both resulted in nothing.

Im not sure what to do at this point.