I select multiple emails, and press "D" to move them to a folder.
Most of the times, only one of the selected message moves. The rest remain in the inbox.

Please, test this using multiple ways to multi-select messages:
- Ctrl + Click
- Arrows (up/down), then Space to select messages.
- Select a message, then Shift + Click to select a range of multiple messages.

Also, while selecting the destination folder, make sure that both Enter and Click works correctly.

Thanks