I see this sometimes importing TV episodes. They do always import eventually, but sometimes it takes a while, and sometimes they don't pick up Cover Art or the correct metadata.
What I found was that some of my TV recordings were corrupted, and MC was getting stuck on Audio Analysis, so the background Auto Import task was never completing. I used a manual run of Auto Import to identify the problem, via the Action Window which showed the process was stuck, and then via logs to identify which file set was corrupted.
So, how does a TV problem have anything to do with not picking up the last track, when the file is obviously there?
As you are using dBpoweramp to rip the CDs, I suspect that the file for the last track isn't being released either by dBpoweramp or by Windows after dBpoweramp finishes with it. The file is still in use, so MC can't write tags to it, which I have no doubt it tries to do as part of the import process, if only to write the file name and path to the file.
So, you have a couple of choices to fix this;
1. Use MC to rip your CDs. It works, although some people have had problems.
2. Either close dBpoweramp after you have ripped a/some CDs, or work out what you have to do in dBpoweramp to force it to release the last file it ripped. Maybe close the ripping dialogue and go back to the menu, or similar? But Windows doesn't release a file sometimes, even when the application using it has closed. So sometimes you just have to wait a bit. Also there may be other applications that touch the file once it is created, such as a virus scanner. A virus scanner shouldn't lock the file though, and hopefully neither should other applications. Is Windows Indexing service turned on for your music location?
3. Manually run Auto Import after ripping a group of CDs, and check that all tracks imported correctly.
Basically, this issue looks like a MC problem, but I suspect that it is actually a Windows/environment problem. Maybe there is something in the logs which would show that the last track wasn't imported, and possibly why, such as file in use. Maybe someone can help in suggesting what to look for in the logs, although just searching for the file name in the log should show something.