Problem with optimizing files on https

Hey!

I came into following problem this evening. I have moved my wordpress site to https. What I did:
– added rewrite rules to .htaccess
– changed site and wordpress url to https
– reinstalled plugin

Now after enabling css and jss combining I can see the following errors in cached files:
Error loading script content: https://url…
I went into plugin code and it looks like wp_remote_get causes error, but don’t know why.

Any hint for that?

https://wordpress.org/plugins/js-css-script-optimizer/