OPK doesn't match CM

Lillo
So per Glow, today is my optimal day. And I've been taking opk for the last week or so, but yesterday and today, the line wasn't getting darker, it was noticeably lighter. Today it is very faint, but I have light EWCM, which is huge for me, as I don't really have much. 
Any ideas?? 

Glow Resources

Let’s Glow

Glow is here for you on your path to pregnancy

Glow helps you navigate your fertility journey with smart tools, personalized insights, and guidance from medical experts who understand what matters most.

25+ million

Users

4.8 stars

200k+ app ratings

20+

Medical advisors