Here a sample survey

Ahh, changing the question format to Y-m-d and now it works like a charm.

one more thing. I am using the basic boostwatch theme and have a modified one where I changed the font color for the Tips and a custom CCS to change the question background to white.

On neither of them the date popup work, but on the imported survey (which also uses bootswatch) when you click the date field it comes up with the Date selector. Am I missing a setting?

It would be interesting to know which solution worked for you.

Regarding the date picker not appearing, do you have any JavaScript errors in the console?

Hi, sorry,
we talked a lot not seeing that you still stayed to your "d/m/Y".
Yes in date/time functions you have to use the database (mysql) format. "Y-m-d".

Two samples at the same time. Tony was a few seconds faster.
Maybe because I am watching the Speed Skating of the Olympics.

Joffm

I've had enough of you Dutch and winning speed skating!!!

Right:

Solution that worked: (strtotime(date('Y-m-d')) - strtotime(CommissionDate.shown)) <= (60 * 60 * 24 * 60)

Imported tpartner's sample

Where can I see console errors?

Click F12 and then "Console".

Ahh, that console.

only a few:

How did you implement the date picker? It looks like it's trying to use jQuery UI whereas it should be using bootstrap-datetimepicker only.

Did you try with a core template?

I am using the main bootstrap template on my survey and it is throwing that error.

Update: same happens with the unmodified vanilla theme too

Can you attach an exported survey containing only that question?