removable device disappear from devices just after mount

The bug occur on thunar-volman v0.9. with thunar v1.8.15, on ArchLinux (both thunar and thunar-volman are not patched after the PKGBUILD), and Manjaro (ArchLinux derived).

The bug is not present on Ubuntu Bionic (thunar 1.6.15, thunar-volman 0.8.1).

I only have this with external USB HDD (Toshiba 4TB external ATA drive: USB ID 0480:0900 Toshiba America Inc MQ04UBF100), that contain a pre-formatted disk, with reserved microsoft and one NTFS partition. The bug doesn't occur with fix local partitions, with another HDD with serveral ext4 partitions or with a USB card reader. I tried with manjaro install cd image on a SDcard, inserted in a USB card reader, at least with ext4 formats.

Il looks like the bug doesn't occur if other partition was already mounted with thunar (not at boot with /etc/fstab).

How to reproduce the bug:

• Boot on the system
• Connect an USB external hard drive with NTFS partition as main partition of the disk
• Click on a device to mount it, it is mounted and then disappear from devices list.
• close all thunar windows, reopen one, and it is again shown in devices list