Ran into this issue twice now. Had a podspec without a period at the end of the summary. Cocoapods flagged it as a warning during pod push saying that summary should end with period. Then promptly failed validation with no errors mentioned.
Re-ran with --allow-warnings, cocoapods still failed with no errors, and no indication as to what the problem was.
Added the period to the end of the summary, pod push worked.
If cocoapods is going to police grammar, it should at least be classified as warning, and --allow-warnings should disable the grammar based validation failure.
This started happening after upgrading to 0.17.0 rc2
[Command::Push] Respect allow warnings option