If you see something weird in google webmaster from indexing point of view then don’t panic. In the recent tweet John Mueller of Google said “We never index all known URL’s” and also said its “pretty normal”.
This issue got attention after a complaint regarding less pages getting indexed was reported. This page were submitted through google stiemap and were not indexed by google. You can see from the image below
Check this tweet from John
We never index all known URLs, that's pretty normal. I'd focus on making the site awesome and inspiring, then things usually work out better.
— John ☆.o(≧▽≦)o.☆ (@JohnMu) January 3, 2018
You don’t need to panic on this, you can focus on your most important pages instead on making lot of pages of every keyword.
News source @seoroundtable