Thumbnails not loaded via https

Hi there, I hope some can help me:

We’ve changed base URL to https (due to German law requirements). On the startpage I call the last posts via mini-loops with this code:

[miniloop number_posts=10]
<ul>
	<li>
<h3><a href="{ml_url}">{title}</a></h3>
{image width=150 height=150 class=alignleft}{ml_excerpt wlength=30 up_to_more=1 after= weiter lesen... space_between=1}</li>
</ul>
[/miniloop]

Thus the image thumbnails are inserted, only they are enbedded via
src=”http://…” instead of src=”https://…” which results in a security warning of browsers.

I can’t find where I can change the behavior how src-path is written…?

Best regards,
nici-

https://wordpress.org/plugins/mini-loops/