Issues Sending Emails from Shared Mailboxes in New Outlook

I've started using New Outlook on Windows 11, and I've encountered a frustrating issue. When trying to send emails from a shared mailbox—whether composing a new email, replying, or forwarding—I keep getting an error that says 'Please wait to send; Attachments are still loading.' This happens even when I send a plain text email without attachments or links. After a short wait, I can finally send the email, but it's quite annoying. I've checked all settings and haven't found anything that explains this issue, nor can I find any information online. Is this a new bug in New Outlook, or has anyone else experienced this? Oddly, other users I've set up with New Outlook haven't reported similar problems.