Launching Acrobat (full version) with a URL in the Path

We have a webdav server.

I can start Acrobat DC (or Acrobat Reader), go to File -> Open, and where it says "File Name:" I can enter the URL of a file on my webdav server, e.g. http://webdav.mycompany.com/docs/myfile.pdf

It opens perfectly, I can edit the file, and I CAN SAVE IT BACK TO THE SERVER - because this is webdav (something that apparently a lot of people don't know exists... see for example the final reply here: https://acrobatusers.com/forum/collaboration-commenting/open-pdf-file-http-url-through-command-line-option/  )

All well and good.

The problem is that if I try to do the same thing by opening acrobat from the command line, with the URL as a parameter, like so:
> acrord32 http://webdav.mycompany.com/docs/myfile.pdf
or

> acrord32 "http://webdav.mycompany.com/docs/myfile.pdf"

I get:

There was an error opening this document. The filename, directory name, or volume label syntax is incorrect.

Am I missing a command line argument or something?

If not, doesn't that seem like a bug - that I can then go to the file box in the application, enter the EXACT SAME PATH, and it opens fine?

Thanks,

Chris