Hi@bluelemon247,
Based on the issue that you mentioned, do you want to populate the TextInput control based on the Dropdown selected?
Could you please tell me that if both of the 'JobTypes' and 'Price' are Text type?
I think there is something syntax wrong with your Distinct() function.
I have a test on my side, please take a try as below.
In my scenario, I have 2 Text columns, 'JobTypes' and 'Price'.
Set the Items property of the Dropdown as below:
Distinct(UploadVedio,JobTypes)
Set the Default property of the TextInput control as below:
LookUp(UploadVedio,JobTypes=Dropdown1.Selected.Result,Price)
Note: The 'UploadVedio' is my SP list name, please replace it with yours.

Please check the screenshot and take a try.
Hope it could help.
Best Regards,
Qi