Hi @arnedc
Thank you for your report!
The issue you're describing was fixed with the release of v3.5.0 (https://mattermost.atlassian.net/browse/PLT-4261).
Please try updating your version of the Desktop app - v3.6 has just been released and can be downloaded from this page.
You can also try updating your version of Mattermost Enterprise Edition to v3.6, also available on the "download" page (link above).
Let us know if this works!
Thanks!