Hi @PR1,
Could you please share a bit more about the issue on your side?
How do you take/upload the picture within your app? Using Camera control or Add picture control?
Further, could you please share a screenshot about your app's configuration?
I assume that you taken the picture using Camera control within your app, I have made a test on my side, and don't have the issue that you mentioned. The screenshot as below:
Flow's configuration:
Within "Create file" action, set the File content field to following formula:
dataUriToBinary(triggerBody()['Createfile_FileContent'])
App's configuration:

Set the OnSelect property of the "Upload" button to following:
Set(UrlLink,'20181005_case6'.Run(TextInput1.Text&".jpg",Camera1.Photo))
The flow works successfully as below:
The uploaded picture as below:


If you use Add picture control to capture the picture that you want to upload to your SP library, I think there is something wrong with your flow's configuration. The picture the Add picture control captured would return a blob data rather than a Image URl Data, so the dataUriToBinary() function within your flow would not work.
If you want to upload a picture captured via Add picture control from PowerApps to SP library, please check the following blog:
http://repointtechnologies.com/saving-images-from-powerapps-to-sharepoint/
In addition, the MVP user @John Liu has found a simplest solution to upload a picture captured via Add picture control from PowerApps to SP library. Please check and see the following blog:
http://johnliu.net/blog/2018/7/the-simplest-no-code-solution-to-save-pictures-files-from-powerapps-to-flow
Best regards,
Kris