SPPID_Can not break the line between two nozzles

In order to put the Heat Tracing segment break in the middle of two nozzles. We need break the line between two nozzles. Most of times, we can break the line easily, but sometimes, we can not. Why?

Here is one reason:

See the end of right nozzle, there is an inconsistency. If you click the right line, then break in the middle of nozzles. It won't work because the inconsistency. It you can not break a line with different information. either you need fix the inconsistency first or click the left line, then break in the middle of nozzle. It will works.

again: if you just put the Heat Tracing break at the middle of two nozzles. you can put the label on it, but it doesn't work. The Administrator may receive complain: the Heat Tracing break doesn't work. actually, the line hasn't yet broken.