I'm currently developing a web add-in for my organization. In the taskpane, I am using a .aspx file hosted on my organization's SharePoint.
In my manifest file, the URL appears something like this:
<bt:Url id="FabReleaseTaskpane.Url" DefaultValue="https://myorg.sharepoint.com/sites/mySite/SiteContentProduction/AddInContent/NameofAddin/taskpane_FabRelease.aspx"/>
When debugging and running the add-in through the browser-based version of Outlook (OWA), there are no issues and the taskpane loads the .aspx content perfectly. I believe this is likely due to the fact that I am already authenticated in the browser version of Outlook while the desktop version requires extra authentication.
However, an issue arises when running the add-in on the desktop version of classic Outlook (Specifically, Microsoft® Outlook® for Microsoft 365 MSO (Version 2312 Build 16.0.17126.20190) 64-bit).
The issue on the desktop version is that once the button for the add-in is clicked and the taskpane opens; the taskpane appears blank. At the same time, a webpage opens in my browser to authenticate me with SharePoint and redirects me to my organization's homepage for SharePoint. Unfortunately, after this authentication completes, there is still no updates to the blank taskpane and it remains the same without rendering the .aspx
There shouldn't be any permission issues with the sharepoint page and scripts are already enabled. Additionally, the issue shouldn't be related to my code since there is no authentication in my code. I have included a GIF below demonstrating the steps I took that result in this problem. If any other information is needed such as a full copy of my manifest file, let me know. I would appreciate a suitable solution for my issue.