Snap upload fails

Since push has been replaced with upload I can’t do any releases anymore.
It doesn’t really give me an error that tells me how to solve the problem. I already send an anonymous report, but is there a workaround?

/mnt/data/code/cordless (master)$ snapcraft upload --release=stable "cordless_${RELEASE_DATE}_multi.snap"
Preparing to upload 'cordless_2020-06-26_multi.snap'.
After uploading, the resulting snap revision will be released to 'stable' when it passes the Snap Store review.
Running the review tools before pushing this snap to the Snap Store.
Sorry, an error occurred in Snapcraft:
Command '['/snap/bin/review-tools.snap-review', '/mnt/data/code/cordless/cordless_2020-06-26_multi.snap', '--json', '--allow-classic']' returned non-zero exit status 1.
We would appreciate it if you anonymously reported this issue.
No other data than the traceback and the version of snapcraft in use will be sent.
Would you like to send this error data? (Yes/No/Always/View) [no]: v
Traceback (most recent call last):
  File "/snap/snapcraft/4892/bin/snapcraft", line 11, in <module>
    load_entry_point('snapcraft==4.0.5', 'console_scripts', 'snapcraft')()
  File "/snap/snapcraft/4892/lib/python3.6/site-packages/click/core.py", line 829, in __call__
    return self.main(*args, **kwargs)
  File "/snap/snapcraft/4892/lib/python3.6/site-packages/click/core.py", line 782, in main
    rv = self.invoke(ctx)
  File "/snap/snapcraft/4892/lib/python3.6/site-packages/click/core.py", line 1259, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/snap/snapcraft/4892/lib/python3.6/site-packages/click/core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/snap/snapcraft/4892/lib/python3.6/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "/snap/snapcraft/4892/lib/python3.6/site-packages/snapcraft/cli/store.py", line 186, in upload
    review_snap(snap_file=snap_file)
  File "/snap/snapcraft/4892/lib/python3.6/site-packages/snapcraft/cli/_review.py", line 33, in review_snap
    review_tools.run(snap_filename=snap_file)
  File "/snap/snapcraft/4892/lib/python3.6/site-packages/snapcraft/internal/review_tools/_runner.py", line 43, in run
    subprocess.check_output(command, stderr=subprocess.STDOUT, env=env)
  File "/snap/snapcraft/4892/usr/lib/python3.6/subprocess.py", line 356, in check_output
    **kwargs).stdout
  File "/snap/snapcraft/4892/usr/lib/python3.6/subprocess.py", line 438, in run
    output=stdout, stderr=stderr)
subprocess.CalledProcessError: Command '['/snap/bin/review-tools.snap-review', '/mnt/data/code/cordless/cordless_2020-06-26_multi.snap', '--json', '--allow-classic']' returned non-zero exit status 1.
We would appreciate it if you anonymously reported this issue.
No other data than the traceback and the version of snapcraft in use will be sent.

Btw, I am on ubuntu 20.04 with the latest snapcraft installed via snap.