A solid line indicates that there is an envelope present up to measure 238. Are you actually using pan automation or is it just flat throughout? There must be a pan node at 238. The dotted line usually indicates no further automation on the envelope but a jump segment will also be dotted, so it is possible there's a further node after the line turns dotted. (Hope that makes sense)

If you are using automation I'd suggest inserting a node on the pan envelope at the end of the last clip on that track, then delete the node at 238 by right clicking on it and selecting "Delete node"

If you aren't using the envelope at all just right click anywhere on the envelope and select "Delete envelope".

In either case you'll need to set the edit filter to the pan envelope first (Shift + left click on it).

That should sort it out.

Select all tracks and time range you want to delete automation from, then select "Edit--->Delete....." from the menu. You'll then have the option to uncheck "Events in tracks", make sure track automation is checked and click on okay.

Select all of your Midi clips and do a bounce to clip (assuming you don't have any Midi Clip Fx anywhere)

See if any of them extend out after the bounce.