Response body from API call is not set in variable

In my Bubble app, I’m calling a HTTP endpoint using a POST request. The variable of the returned body does not contain the resulting value. Also, in the log entries, no return data is visible at all:

I know it works using Postman. Strangely, I can initialize the call using the plugin page, and the structure correctly gets recognized in Bubble. It seems to me that Bubble somehow retrieves and parses the JSON correctly. (the “otherValue” was a temporary field during tests, removed again):

This is what Microsoft Flow returns (depending on the situation, left or right):

Also, I can clearly say that the variable is not being set, because I’m sending an email containing the variable to check:

Any idea what else I can try is much appreciated - Thank you.