Some info:

• SMAPI log shows no error when this behaviour happens.
• When it throws the items you just put in the chest on the ground a SFX can be heard. Sounds like an error SFX.
• A second trash can is briefly shown in the menu, next to the chest grid.
• Dragging no longer works (I don't remember if it was ever a SDV feature while in chests…).
• Only right clicking works reliably… Sometimes we trick it by right-clicking once or twice and then left-clicking.

I'll try to provide a video in the next couple days!