What is the deal?

Windows 10, version 3.0.0. for some reason, I can’t get the new version to recognize line in…I want to record from a reel to reel tape deck, using every output source from my receiver. The earlier version (2. something) did not have any problem. What am I doing wrong?
Also, when I record from let’s say Youtube, the record progress “cursor” starts, stops and starts stops. What is up with that? Again, never had that problem with the earlier version.

When was that? 10 minutes ago or weeks / months ago?

(If there have been any Windows updates since you used Audacity 2.x, that could account for the change, in which case we are looking at getting Audacity to work with the computer system as it is now.)

Well, I had the earlier version installed until about 2 weeks ago. I would not be surprised that a Windows update has screwed up 3.0.0. It didn’t seem to do that to the previous version. Is the previous version available?

Yes, Audacity 2.4.2 is available from FossHub: https://www.fosshub.com/Audacity-old.html

Also, Audacity 3.0.1 is scheduled for release later this month. Worth giving that a go when it comes out.

So when you are recording using WINDOWS WASAPI, Windows waits until the source starts providing audio before it passes anything along to Audacity. Not so with MME.

Also, check that you are not using Sound Activated Recording. https://manual.audacityteam.org/man/recording_preferences.html#:~:text=Sound%20Activated%20Recording%3A%20Enables%20or,(see%20the%20item%20below).