VBA used to allow multiple drop down selections in one cell causing date format to change.

Hello,

I'm very new to excel spreadsheets and so far have got on quite well.

I'm creating a sheet to be able to make multiple selections in one call using validation tool and also a code I had found that is required to do so.

The code works great except for some reason when running any date I input in UK auto changes to US format.

It is linked to the code as the moment I delete it, the issue resolves.

Hoping someone can check the code and see what might be the cause and if possible to correct without affecting the codes ability to do what is needed.

HTML Code: 

Thanks.