Nightly alpha.1.149+g6a716fa5f: MIDI stops working after certain amount of time

### Bug Summary

After playing for a certain amount of time (ca 1-3 min), the MIDI input stops working. The last played keys will be played constantly until the same key is clicked, re enabling input. Keys will stay green until clicked with a mouse or overridden by new MIDI input on the same key.

#### Steps to reproduce

1. Open an instrument
2. Play notes for 2-3 minutes
3. Bug occurs

#### Expected behavior

MIDI input continues to get recognized.

#### Actual behavior

MIDI input stops working until instrument and affected notes are clicked again

#### Screenshot
After MIDI input stops working

#### Affected LMMS versions

alpha.1.149+g6a716fa5f

#### Logs

Click to expand

No error logs produced

#### System Info
Arch Linux 5.15.5-arch1-1
Desktop Environment: KDE Plasma
Audio: pipewire with pipewire-pulse pipewire-jack pipewire-alsa
MIDI input: ALSA Raw-MIDI (Advanced Linux Sound Architecture)

Reproduce the issue in LMMS by opening an instrument and playing MIDI notes for 2–3 minutes using ALSA Raw-MIDI on Linux. Start by tracing the MIDI input handling and note-release behavior; done means MIDI continues to be recognized and no notes remain stuck without mouse interaction.

Written by the indexing model from the issue text.