The selection has disappeared

Grasshopper
1

Hi, I have a problem with previewing on grasshopper. When you select a curve, instead of turning green it disappears. Shortly before encountering the problem, I had inserted an “evaluete curve” and something else, and by removing them the tragedy arrived.

Thanks to the availability

2

Hi,

Is it possible to upload the incriminated file ?
Did you check if that problem expanded to other files/new files, or only the one you are working on ?

3

Hi, I solved the problem by restarting Rhinoceros, but I don’t know what could have been the cause.
Thanks for your time