Discovery rule with HTTP Agent and converted JSON gives errors

[mariusl]

Following up on my post in another thread, i'm having issues with properly handling converted JSON data from HTTP agent in a discovery rule.
I am doing a simple request to an URL that returns a value in clear text, as example

mydata=0

I'm using the function in HTTP agent to convert this to JSON which returns

{"body":"mydata=0"}

Notice how it does not add an array.

Using this, i'm getting multiple errors. Without defining any LLD Macros i get

Cannot find the "data" array in the received JSON object.

.
Adding a macro with JSONPath $.body or $..body gives the same error.
Using JSONPath $.. gives

Cannot process LLD macro "{#UNIT_ID}": jsonpath was unexpectedly terminated.

I have also tried JSONPath $.* and $..*, both giving errors.
There are no preprocessing steps added.

I'm starting to think that the "Convert to JSON" should have wrapped the data in an array. Perhaps there is a bug?
Anyone else have some suggestions to what i could try, or can point out what i may be doing wrong?

Thank you!