[Plugin: Related Posts Thumbnails] Problem with w3 Total Cache

Hi,
I use

<?php get_related_posts_thumbnails(); ?>
<?php get_related_posts_thumbnails('random'); ?>

because I have two blocks the 1st one loads from all the posts and the second one loads random posts so it doesn’t repeat the posts in the two blocks. But When w3 Total Cache is active I have 2 problems:
1) It shows into both of the blocks the same posts
2) When the page is reloaded the posts are always the same doesn’t change nothing.

I tried with fragment caching;

<!-- mfunc
<?php get_related_posts_thumbnails(); ?>
<?php get_related_posts_thumbnails('random'); ?>
-->
<!-- /mfunc -->

but it prints out some messed up stuff and there’s no posts
but only this html stuff printed like normal text.

https://i.imgur.com/D5L1j.png
this is an image with the first block with the 4 boxes
below there’s another block with 4 boxes that shows the same stuff when w3 Total Cache is active

p.s. Everything works fine when the w3 Total Cache isn’t activated.

thank you very much!

https://www.ads-software.com/extend/plugins/related-posts-thumbnails/