Open URL with app fails but using New Google Chrome Tab works

I can't figure out why my macro fails if I try to open the Bear app using the Open URL action, but it works if I open it using the New Chrome Tab with URL action (and then press OK to the dialogue that opens it in Bear, of course).

Here is my encoded URL:

bear://x-callback-url/create?title=FIXME&tags=notabilia/raw&text=Papworth%0A%0A%2D%2D%2DFIXME%20%20%0A%2D%2D%2Dfound%20in%20

The error in the log file is:

2020-09-27 19:07:34 Open URL failed with invalid URL “%Variable%BEAR_Callback%” In macro “Bear: Notabilia New” (while executing Open URL “%Variable%BEAR_Callback%”).

Here the two actions (I only enable one of them when the macro is active), the latter works:

Have you tried using the Open a URL action using "default application"?