Preloading stopped working after some time

I just installed WP Super Cache plugin and among all other configurations, I started preloading of all my posts/pages. I’ve like 350 of them. Preloading was working fine for a while and I was monitoring it but it stopped working after like 135 posts and its hasnt progressed after that.

The preloading tab is still showing that posts 100 to 200 are being preloading but its not progressing.

Any idea what could be the issue?

https://ww.wp.xz.cn/plugins/wp-super-cache/