Thanks for the update, Craig.
Since this seem to be an issue with Excel Online exclusively, it cannot be resolved normally by just reinstalling Office or trying a different web browser than the one you are using right now. Thus, you need to provide this experience as feedback to our developers using the steps in the link below.
https://support.microsoft.com/en-us/office/how-do-i-give-feedback-on-microsoft-365-2b102d44-b43f-4dd2-9ff4-23cf144cfb11#platform=Office_for_the_web
As explained in the link above: "We’d love to hear from you about what’s working well, what’s not, and any ideas for improvements including possible new features and functions. Your input will help us improve the user experience for you and all Microsoft 365 users worldwide."
"To make your feedback more actionable, please include a screenshot (where applicable). Also, preferably, select the option to allow us to contact you, then provide your email address."
Thanks again for choosing Microsoft! We’re here when you need us.
Respectfully,
Glenn