Hi @Dante DiPirro ,
What's the specific version of your Outlook 365(File>Office account>About Outlook ), please first ensure that you have updated to the latest version of Outlook. And I would like to confirm if you could paste the text in other programs when the issue occurred(such as Notepad or others).
If you couldn't paste it anywhere, the issue may be related to your client, according to my tests on multiple version of Outlook, I could copy and paste all text normally from Outlook message to word, which seems to I couldn't reproduce your issue. Based on my research, I found some similar thread that mentioned some add-ins may cause it, in this case, it's recommended to restart your Outlook in safe mode directly when the issue occurs in next time(Windows + R > type "outlook.exe /safe"> enter).
If it could work normally in safe mode, we could try to disable the add-ins gradually to check which causes the issue(File>Options>Add-ins, COM add-ins,Go>uncheck the add-in to disable it)
Also, consideirng other third-party programs may also affect the issue, if it possible, it's suggested to close other programs or perform a clean boot in windows directly to check.
Hope that would be helpful to you.
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