Yes this is a bug that will happen on any fitting/ route segment in tube and pipe. It normally happens if you copy a fitting and reuse instead of using place fitting. It is normally resolved by doing a component replace of another fitting then the delete shows up and then you can delete. Not sure what is happening here? Have you deleted the route and the pipe segments stayed behind?
I use an iLogic rule to delete these troublesome parts, less clicks than component replace and sometimes parts fail to replace.
You can use an iLogic rule to delete the pipe segment occurence. The selection tool will allow you to pick the part and then when you press esc you can delete the part. Be careful as there is no built in cancel button. Save before you run the rule and pick the level you want to be, in this case a run. You can undo the change with the undo button.
To use copy and paste the rule to ilogic editor either internal or external. Use internal to get you going fast.
https://adndevblog.typepad.com/manufacturing/2013/11/do-selection-from-ilogic.html
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Regards
Alan