I am currently having an issue when deleting tracks, where the rats nest disappears. In the previous version (V18) I could simply "forward design changes" from the schematic, and they would reappear. However, I am just getting the "designs are the same" dialog box, and no rats nests. Am I missing something here?
Just wondering on your Settings=>Preferences=>PCB Interaction. DELETE can also delete the connectivity and so the "elastic band" will also be deleted. Using BACKSPACE instead overcomes this issue and only removes a segment of track,keeping the connectivity. Forward Design Change from Schematic may not solve the issue as nothing in the schematic has changed. Try Tools=> Integrity Check first.