Excel hide column and protect

JeanMP 

With your permission, knowing the exact Excel version (e.g. 365 Home - not just 365) and the exact operating system (e.g. Win10 (20H2)) would be an advantage for everyone. Of course, it would help everyone if you uploaded an Excel file (with no sensitive data).
With this you could see the error directly and fix it. No picture please, even if it is said that a picture can say a thousand words, Excel certainly does not, on the contrary in some cases.
All of this would also be a blessing for all of us, as we can understand the problem much better, a win-win situation for everyone.

For your problem, I can recommend that you click the "Protect worksheet and contents of locked cells" box when locking the worksheet when locking the worksheet. If you have locked the worksheet with VBA, I recommend locking the VBA project.
But as I said, without knowing which version of Excel it is and which digital environment as far as the operating system or network is concerned, I cannot offer you a specific proposal for a solution.

Thank you for your understanding and patience

Nikolino

I know I don't know anything (Socrates)