Comment 34 for bug 1773897

I have the same issue. Running Linux Mint with latest kernel.
Kernel: Linux 4.19.9-041909-generic #201812130432 SMP Thu Dec 13 09:34:53 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

It takes me disabling bluetooth, deleting the profile, re-enabling bluetooth, and putting the mouse back in pairing mode to fix.

Only began happening after updating from Linux Mint 19 from Linux Mint 18.3 (I assume due to the Bluez version)

dmesg:
[ 9094.174854] Bluetooth: hci0: last event is not cmd complete (0x0f)
[ 9113.487898] Bluetooth: hci0: last event is not cmd complete (0x0f)
[ 9129.243872] Bluetooth: hci0: last event is not cmd complete (0x0f)
[ 9145.487806] Bluetooth: hci0: last event is not cmd complete (0x0f)
[ 9155.351840] Bluetooth: hci0: last event is not cmd complete (0x0f)
[ 9171.601996] Bluetooth: hci0: last event is not cmd complete (0x0f)
[ 9187.474873] Bluetooth: hci0: last event is not cmd complete (0x0f)
[ 9193.843245] Bluetooth: HIDP (Human Interface Emulation) ver 1.2
[ 9193.843255] Bluetooth: HIDP socket layer initialized
[ 9194.686585] hid-generic 0005:046D:B016.0002: unknown main item tag 0x0
[ 9194.686700] input: Bluetooth Mouse M336/M337/M535 Mouse as /devices/pci0000:00/0000:00:14.0/usb1/1-7/1-7:1.0/bluetooth/hci0/hci0:256/0005:046D:B016.0002/input/input27
[ 9194.687692] input: Bluetooth Mouse M336/M337/M535 Consumer Control as /devices/pci0000:00/0000:00:14.0/usb1/1-7/1-7:1.0/bluetooth/hci0/hci0:256/0005:046D:B016.0002/input/input28
[ 9194.687919] input: Bluetooth Mouse M336/M337/M535 Keyboard as /devices/pci0000:00/0000:00:14.0/usb1/1-7/1-7:1.0/bluetooth/hci0/hci0:256/0005:046D:B016.0002/input/input31
[ 9194.688328] hid-generic 0005:046D:B016.0002: input,hidraw1: BLUETOOTH HID v12.03 Mouse [Bluetooth Mouse M336/M337/M535] on a4:34:d9:e0:9c:d1