Forms design on one spreadsheet, not in another

I’m having a problem with my work spreadsheet (it does my tax, and makes a csv for my calendar, so I know what I’m doing, and where I’m going, how much I expect to get for the job, and how much tax I’ve to pay. I’m quite proud of it.

I thought it would be a good idea to have a drop down calendar in the fields of the date column, so I looked at forms control, and found most of them were greyed out (Sorry, I’m a Brit, we spell colours different from you).
See here

So anyway I came here and it was suggested I follow a link to clear my profile, and start again. I did so and it did not clear the problem. So I put the old profile back again. After a few beers, a sleep and some Panadol (British analgesic), I had this crazy idea just to start a new empty spreadsheet and see if the forms icons would come up all pretty colours… They did.
As in here

Anybody any ideas how to get my original spreadsheet to behave?

Thanks.

@Fitch Have tried many ways to duplicate your problem without success. Here is another ‘Shot-in-the-Dark’. Make a copy of your sheet - maybe even with a different name or in another directory and see if that works. Otherwise I see no other way except to post a sample of your document without personal or confidential information in it.

Really sorry for this.

Thanks for the comment.

The damn sheet was protected.

Oops!

Just glad you got it working.