Hi @mhopson ,
Welcome to our forum.
Based on myt test, I could create and sync the siganture normally on my outlook. com account. So if it's possible, it's suggested to log in other accounts on your browser to test if you could save the signature normally, if the issue only occurred on your account, it's recommended to contact outlook. com support directly via click the "?" sign on the upper right part of your Outlook .com page, then click Help.
Also, please kindly understand here we mainly focus on general issue about Outlook desktop client, considering your issue may be related to outlook. com account instead of Outlook client, if you still need further assistance about it, it's suggested to post your issue in this dedicated outlook.com forum
The reason why we recommend posting appropriately is you will get the most qualified pool of respondents, and other partners who read the forums regularly can either share their knowledge or learn from your interaction with us. Thanks for your understanding and hope your question will be resolved soon.
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