No Notification of Best Offers via eBay Messages
The issue is in the title: on several occasions, a buyer submitted a Best Offer and I didn't receive a notification in eBay's messages. No, this isn't an account settings issue: plenty of times I receive Best Offer notifications in eBay Messages, but not always.
I think this issue is more prevalent than people notice. The reason I noticed was because I was checking my eBay-connected email inbox and noticed a Best Offer email from the week before, but didn't receive an eBay Messages message. I check this email mailbox maybe once per month because I rely on eBay Messages to communicate with buyers and receive Best Offers, which I don't think is unreasonable. Obviously, the offer was expired.
Then, I decided to check all the Best Offer messages I received in the last 45 days, for both of my eBay accounts, and compare the number of times I received an email versus an eBay Messages message. I have 2 eBay accounts and, by practice, I access each eBay account from a separate browser when on desktop (one Chrome, the other FIrefox), from different eBay apps on different phones when mobile, and they're connected to different email mailboxes. In the last 45 days, I received 17 Best Offers emails in my email mailboxes, but only received an eBay Messages message for 12 of them. Hence, 5 Best Offers expired long before I saw them.
I suspect this is more prevalent than people realize because (1) eBay Messages isn't consistently failing to notify of Best Offers--only 30% of the time, based on my statistically insignificant sample size; (2) this has happened on both my eBay accounts; so, it's not an account settings issue specific to me, and (3) sellers won't know unless they're periodically auditing their email messages against their eBay Messages. Even though higher volume sellers might find a handful of missing Best Offers from eBay Messages, they don't have time to sort through hundreds of emails a month and compare messages across systems, while lower volume sellers might dismiss a missing Best Offer from eBay Messages as a glitch.