Hi Sir ,
I switched my theme from Classic to Modern into theme option == General setting .
Now the issue to select categorie come back again , i m not able to select any categorie when i open my website on phone. it work perfectly for computer or tablet. it seems this issue is related to small screen.
Also , i have a lot of categories and some Categories are hide when i drop down the Categories TAB .
Please Check the picture below for more information.
thanks all for your assist