Problem is not occurring when tested at 14/Dec/2021 07:30 AEDT with Firefox v95.0.
Firefox version 95.0 appears to have problems loading Office web add-ins like Janusseal App for Outlook.
When attempting to bring up Janusseal App in the side pane when composing a new message, an Add-in Error is shown in yellow stating:
Something went wrong and we couldn't start this add-in. Please try again later or contact your system administrator.
This error also appears with other Office add-ins and is due to an underlying problem in Firefox 95 and Exchange Online.
Other error observed when an end-user attempts to send a message from Firefox, in the notifications area of the message bar:
We're sorry, we couldn't access Janusseal App. Make sure you have a network connection. If the problem continues, please try again later.
The same issue is occurring for other Office add-ins like Microsoft's My Templates and Viva Insights, so it is a common issue when using Firefox 95 with Office web add-ins.
The link above works fine in Edge and Chrome, but fails in Firefox 95 with error
An error occurred during a connection to appsforoffice.microsoft.com. The OCSP response does not include a status for the certificate being verified.
Error code: MOZILLA_PKIX_ERROR_OCSP_RESPONSE_FOR_CERT_MISSING
We are investigating if there is any settings work-around in Firefox to avoid this check for the short term.
We have reported this OCSP error to Microsoft and are awaiting a response from them.
Recommend end-users use an alternative browser while Janusnet continues investigation.