How to convert curl --request PUT (file) into a Tasker HTTP Request PUT (file) that works!

I'm trying to convert a curl shell command into an HTTP action put can't get it to work. I need a solution to this because the target system is Android 8 which doesn't include the curl shell command.

Shell command:

curl --request PUT --upload-file "%tempfile" -k https://mysite.com/uploads/

This works.

Tasker action:

HTTP Request PUT

URL

https://mysite.com/uploads/

Headers

Content-Type:text/plain

Content-Length:%len

File to Send

%tempfile

This gives a response code 200 but no file is stored in "mysite.com/uploads/".

Please anyone :-|