This is what I’ve seen most often in my career. Problem is, the contact is almost always the admin. I’m the admin. Everyone’s idea of assistance is different. Often, I didn’t have the knowledge about the issue in order to be of any assistance. I wound up spending more time running around looking for answers than actually working on what was on my own plate. It’s exhausting. Otherwise known as “please don’t call us for unicorn problems when we handle llamas. Literally, we can’t do anything for unicorn problems.”
I also think you should give this email tactic a try – especially when you return from an extended break or vacation.

When you share transparent business information and provide alternative ways when the relevant channel is not available, it delivers a delightful service experience.
Agreed. I think some people don’t analyze the individual words when they hear the phrase. It’s fine to say “please let me know at YOUR earliest convenience” but it’s weird to say “I’ll get back to you at MY earliest convenience.”