Shipping options not showing to some customers in the UK

Two of my customers contacted me on (May 21, May 26) informing that they cant find shipping options while checking out. They are both in the UK and people have been checking out normally.

I recently added ”Europe” to my allowed shipping location. But I currently removed it because I was afraid this was the reason for this error, since the UK is inside EU so I though this may cause an error.

I am not sure if this issue is now solved or no, but I am afraid it causes me to lose more sales.

It is important to note that this doesnt happen with everyone, so please help me to make sure that this issue does not happen again.

The page I need help with: [log in to see the link]