Anyone know why CallRail isn’t recording all Google Ads calls correctly?

Right now Google Ads shows around 8 calls, but CallRail only recorded 2.

Setup:
• Google Ads call extensions / call ads enabled
• CallRail tracking number pool installed on landing page
• Dynamic number insertion working on website

Trying to understand:
• Does CallRail miss some calls from call extensions?
• Do I need a separate forwarding number setup?
• Could Google Ads be counting clicks as calls?
• Any common setup mistakes between Google Ads + CallRail?

Would appreciate any advice from people who’ve dealt with this before.