E916 error when :PreviewMarkdown on any file

[Schnet]

Hi,

I've installed the plugin as described with Vundle and also installed mdr as well as glow. Whenever I try to get the Preview with :PreviewMarkdown I get the following error:

Error detected while processing function preview_markdown#preview:
line   70:
E916: not a valid job
Press ENTER or type command to continue

then, an new empty window with [No Name] shows up.

I've tried with

let g:preview_markdown_parser = "mdr"

as well as with

let g:preview_markdown_parser = "glow"

, same result.

I've copied the mdr binary into /usr/local/bin and made sure it's in $PATH. When I run

mdr myFile.md

it works just fine.
My vim version is:

VIM - Vi IMproved 8.0 (2016 Sep 12, compiled Mar 18 2020 18:29:15)
Included patches: 1-1453

[skanehira]

@Schnet Can you run this command and let me know that's result?

:echo executable("mdr")

[Schnet]

gives me 1