Vertical line preventing time shift

I’m running 3.2.1 on Windows 10. I’m quite a newbie and evidently lack the correct search terms so hope you can help.
Narrating audiobook, with several pauses, I’ve successfully merged multiple sections (segments?) on the same track. Screen shot attached
Vertical barrier.jpg
shows a gap with a vertical line at 24 mins 30 sec which prevents me merging the section on the right with the section on the left. I don’t know where this came from, what it is or how to get rid of it. I can move it so far as the boundaries of the segments on either side, but even if I move it so as to abut the section on the left and try to draw up the segment on the right to meet it, it prevents a merge. I can only assume I inadvertently activated a shortcut?

Thanks for your help

The vertical barrier is an audio clip, and may be longer than it initially appears,
since non-destructive-editing was recently introduced into Audacity
vertical barrier is some audio.gif
When the “smart” audio clip has been shrunk down to a line,
you need to zoom-in a lot* to be able to expand it back out again.

[ * need to zoom-in until you can see the sample points that the waveform is made up of ].

Brilliant! And easily fixed. Thank you. I’ll remember to take care when editing out audio clips. :smiley: