Sound completely doesn't work on VirtualBox 5.2.28

After installing ReactOS 0.4.13-dev-74-g24647a2 on VirtualBox 5.2.28 and then AC'97 driver from Rapps (with double installation via devmgmt and reboot), there is completely no audio in the guest OS, although "Avance AC'97 Audio" is present in device list and "Works correctly". Even after multiple reboots it doesn't work. Startup sound doesn't play as at the system startup, and from mmsys.cpl or mplay32: after clicking "Play" button in mmsys.cpl or mplay32, nothing happens. Also third-party audio players, like Fox Audio Player 0.10.2 and QMMP 0.11.1 from Rapps can't play any audio files.

After rollback on the previous version 5.2.26, even without reinstalling ReactOS on a VM, sound becomes working with the same VM setting on the same build. After updating to 5.2.28 again, sound doesn't work again.

My audio settings are: Sound driver - "PulseAudio", although I already tried with "ALSA", but it didn't help; and Sound controller ICH AC'97 (XP/2k3-compatible). Host OS - Ubuntu 16.04.6 LTS; kernel - 4.20.16-042016-generic.

By the way, on Win2k3, with the same VM settings on the same VirtualBox version (5.2.28), sound works perfectly "out of the box".

But I still doubt: it's just VBox regression associated with something in audio, which causes sound inoperability only in ROS, but doesn't in Win2k3, or incompatibility with new VBox features introduced in version 5.2.28 on our side...

But judging by https://www.virtualbox.org/wiki/Changelog-5.2, in 5.2.28 were no new features/fixed bugs related to audio. So I'm more inclined to the second case.

Possible source of problem in debug.log:

(drivers/wdm/audio/legacy/wdmaud/control.c:169) Closing mixer B43697A0

(sdk/lib/drivers/sound/mmixer/controls.c:1897) Freeing entry B42E2518

(sdk/lib/drivers/sound/mmixer/mixer.c:140) invalid mixer id 1

(drivers/wdm/audio/legacy/wdmaud/mmixer.c:516) Failed to close mixer for device 1

Besides AC'97 driver, VBox Guest Additions, 7-Zip, Mesa3D and Samba were installed. But on the clear ROS installation + AC'97, is the same situation. As with our portcls.sys, same with MS driver.