Product and categories are partially or never loaded

[mgm175]

Joomla 3.6.5
PHP version  7.1.33
VirtueMart 3.0.18
MariaDB (version unknown, I'm not a server admin)

After selecting in Vertical Menu (from Offlajn) the category, then product, and then again by 3 times in the row, the both product and category is loaded just partially (with cut off "div" etc.), but when I use CTRL-F5 to forcefully refresh, everything gets back to normal, althrough after 3 attempts again, the issue reappears.

The same is showing up when I try to access category and product without using the active Vertical Menu.

Of course, if I disable Vertical Menu, everything is working.

Note: Sometimes this issue dissapear, but usually is very random. I suspect problems with server memory, or cache; although I cannot rule out that Vertical Menu may be bugged, so if needed, I'll send the report to Offlajn.

Live page (note - English language is disabled, Polish is default):
https://globtechnic.pl/pl/produkty

[GJC Web Design]

clicked around and seems fine here  .. all pages load and are reasonably fast

[mgm175]

Thanks for the info, because when I've tried to test around in Firefox 92.0.1 and MS Edge 94.0.992.38, the issue is still showing up (see attachments), both for me and my boss, who told me about that issue.

Strangely enough, after 5 minutes after partial loading of the pages, the pages are loading normally.

[GJC Web Design]

I would suspect server problems more than script problems

[mgm175]

I would suspect server problems more than script problems

It seems so. Boss told me to update from 3.0.18 to the newest version.

Apart from the consequences by this "sudden update", the issue wasn't fixed.

Well, anyway, thanks for the help very much, that would be all.