Cache is generated erratically on multisite’s subsite

I experienced some random problems on my several multisites. Time and again in some moments I see 1) my subsite pages in their original state (without cache) and 2) the queue for optimizing (https://c2n.me/4gzZc4S.png) is stalled, and there is a list of the site’s pages without any actions. However, the cache is generated quickly and thoroughly if I manually input the page’s list (https://c2n.me/4gzZnaa.png). This behavior effectively renders using Seraphinit on my multisites impossible. Why it may be?