HR zones not working?

I've been using the BT logs for several months now, and today, I seemed to have lost the ability to enter the advanced HR data in my log. This changed in the last day or two.

When editing my daily training log, I used to be able to see a button just beneath the Actual area to add the advanced hr info. Clicking the button would add additional fields where I could enter time spent in each zone. That button is no longer there. Instead, I see a link that says "Define a HR zone to enable advanced logging". The zones I defined back in March are still there. I tried editing and saving the existing zones; I tried re-defining the same zones, but no luck.

This is an issue in both Firefox and IE.

Any idea how I can get this to work again? Anyone else having this problem?

Thanks.