shutter asks to "Authorize with Imgur" for each upload to account Imgur OAuth

Every time I upload a screenshot to my imgur account, using shutter account "Imgur OAuth", shutter asks again to "Authorize with Imgur".

I logged in to my imgur account, and I can see that shutter is already authorized, since the first time I went through the OAuth authorization workflow:

https://i.imgur.com/PVgMFy4.png

but shutter doesn't seem to keep the OAuth information, and keeps asking to re-authorize before each upload.

It doesn't matter if the uploads are done within the same shutter session, or if shutter is closed between uploads: it repeats the authorization process for each upload.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: shutter 0.94-1
ProcVersionSignature: Ubuntu 4.15.0-29.31-generic 4.15.18
Uname: Linux 4.15.0-29-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.2
Architecture: amd64
CurrentDesktop: XFCE
Date: Thu Jul 19 17:28:37 2018
InstallationDate: Installed on 2018-04-28 (82 days ago)
InstallationMedia: Xubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
PackageArchitecture: all
SourcePackage: shutter
UpgradeStatus: No upgrade log present (probably fresh install)