FPC cache possibly preventing Amasty One-step Checkout from changing Country selections, and possibly unable to clear cache under certain conditions?

[parserrr]

Hi all!

I searched through the repo issues on Github but I didn't see anything about this, have you heard of any issues regarding Lesti FPC preventing the changing of Allowed Countries to a specific set we chose in our Magento 1.9.3 back end?

We set them in the General config, payment methods and shipping methods (everywhere we could find them), and for the first day, it worked fine. The checkout page only showed our pre-selected list of available countries (listed below). The next day and we noticed they had reverted back to the original full list of ~195 countries.

After clearing the cache and re-checking, sometimes we could get the curated list to show, other times it'd show the full list, with no apparent consistency.

Our initial thinking was that maybe these are unique views on the checkout and the cache files just weren't being cleared when we hit the clear button, and this was further corroborated by watching our cache files for deletion. We've went down this line of thinking because we recently hooked up with some mega affiliates in our niche and our traffic has shot up by like 10,000% in the last couple days, and it got us thinking that maybe the huge uptick was causing large concurrent user spikes that was preventing the cache files from being cleared for some reason - have you heard of anything like this happening?

I ran some empirical tests by waiting until the 'Online Customers' section in Magento's back end showed around 2400 active users (which was a previous number around the time we started watching the user activity), but it actually maxed out at around 3500 yesterday around the time I was originally noticed that clearing all the caches wasn't deleting the cache files in /var/cache/.

Again though this is inconsistent because today with 2400'ish "Online Customers", we were able to clear the cache. I don't know if 1100+ added users would cause enough of a bottleneck or some other race condition to break the clearing. Any info at all on that? I know it sounds kind of 'out there' haha, a 'rm -rf' command initiated by a button press should work one way or another eventually right? :D

I'm just really crossing my fingers you've heard of something. I'm going to attach my fpc.xml file here too so you can see our (very very basic) config to save time (I know I'm throwing a lot at you, I want to optimize any time you may be able to lend me for figuring this out).

Here's the list of selected countries we chose:

France
French Polynesia
Germany
Greece
Hong Kong
India
Ireland
Israel
Italy
Jordan
Malaysia
Netherlands
Norway
South Africa
Span
Sweden
Switzerland
Trinidad and Tobago
United States (default)
United States Virgin Islands

You should be able to see it in action on our site by selecting a Vape Juice and heading off to the Checkout if you'd like. Site: https://hotjuice.com

Or if you need more info from me feel free to reach out.

Thanks so much for any help you can provide!