I'm Miles from the Social Care team at Shopify.
I am sorry you're having so much trouble with adding new collections. We do have an issue where new products and collections are not appearing in searches, and this may be causing the issues you're currently seeing.
If you're ever unsure about something not working as expected, I'd recommend checking out our status page. You can log into your store and view any issues that may be pertaining to your account. You can find the status page here: https://bit.ly/2UAI0Pc.
Please let us know if the issue continues once it's marked as resolved.
I'll let the team know that it's also affecting POS, but not showing on the status page. Please know that we're working hard to fix the issue ASAP for you.
If you have any questions, please let me know.