Tried remove it immediately in the Server settings?

That did not resolve the problem. All that seems to do is not put it in the Trash folder. I need for it to be deleted from the Inbox. The IMAP log shows me that it sets the delete flag, but does not do an expunge until you exit the program. I don't know what is legal in the protocol, but I feel that somehow that is keeping Thunderbird from retrieving new messages. I can see it communicating with the ISP but never returning any messages. I am not sure why but if you let it sit long enough it may start retrieving new messages. I can tell you that my tablet and Windows 10 mail immediately expunge the messages and if I manually delete any one of the emails at the ISP Thunderbird starts retrieving new messages.

until your ISP starts offering a compliant service mail service. that is it wraps folder names in quotes then I see no real solution. I have initiated some correspondence with their supplier, we will just have to see were that takes us.

I would like to draw attention to this bug., as it is your logs that I quote. https://bugzilla.mozilla.org/show_bug.cgi?id=1258429

Even though it is marked invalid (we have no bug charter does) any new information is likely to appear there first.

1. I was told by Charter that they did not create the folder in question. I simply deleted the folders in question as it was obvious they were folders that were added by the user.
2. I thought the problem was that emails were not being deleted. That was because I could delete an email and it would receive new ones. I discovered a way to get Thunderbird to delete the emails in the ISP when they were deleted in Thunderbird. This did not solve the problem.
3. I discovered that when the problem occurs sometimes Thunderbird will start receiving new emails. I started the log and discovered that when Thunderbird checks for new emails it is getting a response that all have been seen, even though that is incorrect. Then all of a sudden, when it decides to work, Thunderbird does something with the connection and then it gets a response that there are new messages. I am trying to figure out what happens. The problem is that I let it sit for hours and it never received new emails. Then sometimes it takes less then an hour.
4. The bug referenced says Charter has a problem, and they may very well, but I would like to point out that my tablet and Windows 10 mail, on the same PC as Thunderbird, do not have a problem.
5. If Charter has a problem then give me something to go back to them with, although it may be wasted since the only people you get to talk with will say over and over they do not have a problem.

I have a question:

I started the IMAP log and let it sit for almost 2 hours. There was an email in my ISP Inbox. Thunderbird is set to check for new messages every 5 minutes. What I see every 5 minutes is net:S-INBOX:ProcessCurrentURL:imap://billcone%40charter%2Enet@mobile.charter.net:993/select%3E/INBOX: = currentUrl with no messages being returned.

I decided to go offline and back online to see what would happen. What I saw was ProcessCurrentURL:imap://billcone%40charter%2Enet@mobile.charter.net:993/select%3E/INBOX: = currentUrl and a little later in the log I see 5 select "INBOX" followed by messages.

My question is does the protocol require a "Select" command every time it needs to check the Inbox?

Another question: Just make sure I was not mistaken I changed Thunderbird so that it would not invoke an expunge when I deleted a message.

1. I sent a message from Windows 10 mail to my Thunderbird account. I started Thunderbird and it showed up in the Thunderbird Inbox.
2. I took Thunderbird down and started it with the IMAP log bat.
3. I deleted the message sent from Windows 10 mail. This removed it from the Thunderbird Inbox and marked it as being read in the ISP Inbox with the message still being displayed in the ISP Inbox.
4. I then sent another mail from Windows 10 mail. The message appeared in the ISP Inbox but would not show in the Thunderbird Inbox.
5. I then deleted the message marked for expunge from the ISP Inbox.

When I did that and clicked on Get Messages the message appeared in the Thunderbird Inbox.

The log showed the following:

1. Prior to deleting the email and performing Get Messages I saw 12 FETCH (FLAGS (\Seen \Deleted NONJUNK) UID 103606). I assume this is what Thunderbird is asking for.
2. After deleting the email and performing Get Messages I saw 12 FETCH (FLAGS (\Recent) UID 103607) with a response of 13 EXISTS.

So this makes me think that for some reason Thunderbird did not ask for any new messages.

What changed?

Why would it all of sudden ask for new messages?

The only difference I see between when it did not get a new message and when it did is flag change. Everything up to that point seems to be the same.