No problem with TalkTalk Mail at https://apps.talktalk.co.uk/appsuite that I can detect. Currently signed in to one mailbox. On another browser signed in to another mailbox ok, signed out and in to another mailbox. All working as expected.
I got a mail notification of your post here and received the same via an email client.
What's happening, or not happening, with your email?
Thanks for taking time out to let us know all's working now. We always appreciate your feedback.
I didn't notice any glitch but grateful thanks for reporting. If there is going to be a problem it often starts with a small glitch that gets auto-repaired / self healed so we'll keep an eye on the platform.