We have the same problem.
To add to the issue, we have been able to save and quit then reconnect spawning in the same location as before with the invisible walls no longer there. Once we saved and quit but were spawned in mid air thus our character died from falling.
Server Version 1.8.0.24
CPU: 2 vCPU, Intel(R) Xeon(R) CPU E5-2673 v4 @ 2.30GHz
RAM: 4GB
Distributor ID: Ubuntu
Description: Ubuntu 18.04.1 LTS
Release: 18.04
Codename: bionic
Realms: 2
Users: 3 (between both realms)
Client Version 1.8.0 - Windows 10
Just checking to see if anyone has confirmed the issue is no longer present in 1.9.0.3 as per @Mega_Spud