Only fraction of the AMP pages are indexed

[Gautam]

Back in June, we had seen a sharp drop in traffic on our website. We initially assumed that it was due to the Core Update that was rolled out in early June.

We had switched from http to https in May, but thought that should have helped rather than cause a problem. Until early June the traffic was trending upwards.

While investigating the issue, I noticed that only a fraction  (25%) of the AMP pages have been indexed. The pages don't seem to be getting indexed even though they are valid.

Accordingly to Google Analytics too, the percentage of AMP traffic has dropped from 67-70% to 40-45%. I wonder if it is due to the indexing issue.

In terms of implementation it seems fine. We are pointing canonical to the AMP page from the desktop version and to the desktop version from the AMP page.

Any tips on how to fix the AMP indexing issue.  Should I be concerned that only a fraction of the AMP pages are indexed.

I really hope you can help in resolving this issue.