We've had an issue with the Desktop client since we updated the tenant with the certificate.
When we start ARIS Architect/Designer, we get the next message:
Since we tried to install the next dialog appeared:
We tried different things with that certificate - installing it manually, etc. - and the result is the same; since you start the app next time, everything repeats again.
When you select the Proceed it allows to start Architect/Designer.