Sound & Video not in sync

I recently recorded 1 1/2 hours of video at my daughter's dance school with the intention of producing a DVD for the other parents.

When I downloaded the video from the camera it was split into 2 clips each 45 mins (this is how the camera software works and has never caused a problem).

I created a project using the first clip and after editing I was left with a perfectly pleasing result, however when I then created another project using the second clip I found that when watching the children singing, the voice and video was slightly out of sync. I tried watching the clip on the laptop using 'Films and TV' and it was fine, I also tried creating a project using the same clips in my old Windows 7 laptop using Premiere Elements 11 and the issue was not present so I conclude that something in Premiere Elements 2018 is introducing the issue.

I'd be very grateful for any suggestions as to how this could be resolved. (Please note that I have rendered the work area).

I am using:

Panasonic HC-V100 camera, file type: m2ts

Dell Inspiron Windows 10 laptop

Premiere Elements 2018 - project settings: PAL AVCHD - Full HD 1080i 25

I previously used Premiere Elements 11 (since 2013) and never experienced this type of issue.