Continuity and Safari Tabs Will Not Work With My XS, But Does With My 5S?

I cannot sort out why MacOS Continuity and Safari iCloud tabs on my MBP (or my 5S) will not recognize my iPhone XS. My MBP recognizes my 5S's tabs.

It has worked sporadically in the past but hasn't worked in over 3 weeks. Oddly, my XS recognizes both my MBP's and 5S's tabs, so the issue is clearly on the MBP side.

Thus far, I have:

- Shut off and restarted all devices too many times to count

- Followed all set-up directions and settings according to Apple's website

- Logged out of iCloud on all devices and logged back in

- Ensured all devices are on the same Wifi network

- Ensured Bluetooth is "On" on all devices

- Paired my XS > MBP over Bluetooth

- Directly USB connected my XS > MBP