PLEASE HELP - Formatting Y axis to display Time in Powerbi Visuals

[FatherLizard]

Ok, so here is the issue I have been struggling with:

I have a dataset that includes duration type data for emergency response and I need to track average durations over time. In excel, this is actually quite simple to do with two columns - 1 with the duration value formatted in decimal type, and 1 with the corresponding date. All I have to do in excel is then create a line chart with average duration on Y and date on X. To format the duration correctly, excel allows me to then select the Y axis to format and choose the 'Time' category to get my decimal values presented as hh:mm:ss. (see below, excel)

In powerbi however, the nightmare begins. There is no way I have found to do this change to format the Y axis while keeping the decimal value as the Y axis reference and retain aggregation. I have attempted to find a similar method to excel but it seems there is no way to solve this.. I am really stuck. Presenting the duration value as a decimal in my visuals is not a suitable option as my users are not going to find any value out this. (see bleow, powerbi)

Any help would be very appreciated.

Thanks.