Second mount of MTP device fails

I have copied some files from my phone to the local disc. I disconnect the phone and plug in my tablet, however I don’t get the KDE “Disks & Devices” pop-up. A journalctl -f shows the following:

omen:/var/log # journalctl -f
– Logs begin at Tue 2020-04-14 15:52:12 BST. –
Nov 02 11:34:27 omen.murorum.me.uk plasmashell[2076]: qt.svg: <input>:413:129: Could not add child element to parent element because the types are incorrect.
Nov 02 11:34:27 omen.murorum.me.uk plasmashell[2076]: qt.svg: <input>:413:379: Could not add child element to parent element because the types are incorrect.
Nov 02 11:34:27 omen.murorum.me.uk plasmashell[2076]: qt.svg: <input>:413:631: Could not add child element to parent element because the types are incorrect.
Nov 02 11:34:27 omen.murorum.me.uk udisksd[1645]: Unmounted /dev/sdb1 on behalf of uid 1000
Nov 02 11:34:27 omen.murorum.me.uk kernel: sdb: detected capacity change from 32395755520 to 0
Nov 02 11:34:27 omen.murorum.me.uk plasmashell[2076]: file:///usr/share/plasma/plasmoids/org.kde.plasma.devicenotifier/contents/ui/DeviceItem.qml:160:5: Unable to assign [undefined] to QString
Nov 02 11:34:27 omen.murorum.me.uk kiod5[12076]: kf5.kiod.kmtpd: New device attached with udi= “/org/freedesktop/UDisks2/block_devices/sdb” . Checking if PortableMediaPlayer…
Nov 02 11:34:27 omen.murorum.me.uk plasmashell[2076]: file:///usr/share/plasma/plasmoids/org.kde.plasma.devicenotifier/contents/ui/DeviceItem.qml:195: TypeError: Value is undefined and could not be converte
d to an object
Nov 02 11:34:27 omen.murorum.me.uk plasmashell[2076]: file:///usr/share/plasma/plasmoids/org.kde.plasma.devicenotifier/contents/ui/DeviceItem.qml:202: TypeError: Value is undefined and could not be converte
d to an object
Nov 02 11:34:32 omen.murorum.me.uk plasmashell[2076]: file:///usr/lib64/qt5/qml/org/kde/plasma/extras/ExpandableListItem.qml:314: TypeError: Cannot read property ‘width’ of null
Nov 02 11:36:38 omen.murorum.me.uk rtkit-daemon[2130]: Supervising 4 threads of 3 processes of 1 users.
Nov 02 11:36:38 omen.murorum.me.uk rtkit-daemon[2130]: Supervising 4 threads of 3 processes of 1 users.
Nov 02 11:37:26 omen.murorum.me.uk nscd[958]: 958 checking for monitored file /etc/services': No such file or directory** Nov 02 11:37:41 omen.murorum.me.uk nscd[958]: **958 checking for monitored file /etc/services’: No such file or directory

If I reboot the system then the tablet mounts OK. Not sure why this is happening.