Dolphin can not mount iso file. But I can use mount command to mount the iso file successfully.
The Journald log show the Dolphin error:
Error mounting "/home/test/xxxx.iso" : "org.freedesktop.UDisks2.Error.Failed" "Error waiting for loop object after creating '/dev/loop1': Timed out waiting for object"
I find use udisksctl will get the same error but use mount -o loop is OK.
$ udisksctl loop-setup -r -f mydisk.iso
Error setting up loop device for mydisk.iso: GDBus.Error:org.freedesktop.UDisks2.Error.Failed: Error w
aiting for loop object after creating '/dev/loop2': Timed out waiting for object