Swimming Stroke and Distance Detection Problem

I have been using my 745 for swimming for a few weeks without any concerns.

Swimming in the same pool (25m) every time.

This morning when I started the activity I noticed after the first 4 sets that my watch did not pickup any interval distances.

I thought I was doing something wrong so I stopped the activity. With the following completed;

1 x 100 FS in Z2 + 100 Pull in Z2
1 x 50 FS in Z2

I checked the "Pool Swim Settings" and did not find any issues. Pool Size was 25 Meters, Stroke Detection was on, Auto Rest was Off.

I started the training session again and for the entire rest of the swim (2,150m) my watch did not pick up any interval distance.

I pressed the "lap" button every time I had a rest and started the interval every time I kicked off.

Please help?