This is going to blow your mind

[TimberWolf-1533]

Did you download the new patch?

Diablo II: Resurrected | 10.15 - PC/Console Patch Notes - Build 1.0.66578 (Updated on 10/19)

Please note - We have an update hitting PC and Consoles (later this evening on 10/19) that will be Version 1.0.66578. Fixed an issue where exiting the login queue into offline mode early could cause a black loading screen to appear after the player enters offline gameplay

Personally, I never ran into this bug.