Jon, no it didn't make a difference after removing the edits in XML mode. That is one of the first things I did, sorry, I should have mentioned my debugging steps.
I also replicated the issue using a dummy VM:
Made a new Win 10 VM using the same image and made a change to the XML file
Editing in Form view (This works ok, updated fine)
Then I removed my edit in XML view
Made a change in Form view
Pressed Update, now it's stuck in Updating....
So it may be a limitation/bug in Unraid at this point.
Here is my Win 10 XML that is not updating using form view:
<?xml version='1.0' encoding='UTF-8'?>
<domain type='kvm'>
<name>W10_SURVEILLANCE_PC</name>
<uuid>1c7ccfe3-c09d-56a9-f441-de36ef5cd86f</uuid>
<metadata>
<vmtemplate xmlns="unraid" name="Windows 10" icon="windows.png" os="windows10"/>
</metadata>
<memory unit='KiB'>4194304</memory>
<currentMemory unit='KiB'>4194304</currentMemory>
<memoryBacking>
<nosharepages/>
</memoryBacking>
<vcpu placement='static'>8</vcpu>
<cputune>
<vcpupin vcpu='0' cpuset='2'/>
<vcpupin vcpu='1' cpuset='8'/>
<vcpupin vcpu='2' cpuset='3'/>
<vcpupin vcpu='3' cpuset='9'/>
<vcpupin vcpu='4' cpuset='4'/>
<vcpupin vcpu='5' cpuset='10'/>
<vcpupin vcpu='6' cpuset='5'/>
<vcpupin vcpu='7' cpuset='11'/>
</cputune>
<os>
<type arch='x86_64' machine='pc-i440fx-3.0'>hvm</type>
<loader readonly='yes' type='pflash'>/usr/share/qemu/ovmf-x64/OVMF_CODE-pure-efi.fd</loader>
<nvram>/etc/libvirt/qemu/nvram/1c7ccfe3-c09d-56a9-f441-de36ef5cd86f_VARS-pure-efi.fd</nvram>
</os>
<features>
<acpi/>
<apic/>
<hyperv>
<relaxed state='on'/>
<vapic state='on'/>
<spinlocks state='on' retries='8191'/>
<vendor_id state='on' value='none'/>
</hyperv>
</features>
<cpu mode='host-passthrough' check='none'>
<topology sockets='1' cores='4' threads='2'/>
</cpu>
<clock offset='localtime'>
<timer name='hypervclock' present='yes'/>
<timer name='hpet' present='no'/>
</clock>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>restart</on_crash>
<devices>
<emulator>/usr/local/sbin/qemu</emulator>
<disk type='file' device='disk'>
<driver name='qemu' type='raw' cache='writeback'/>
<source file='/mnt/user/domains/Windows 10 - Surveillance PC/vdisk1.img'/>
<target dev='hdc' bus='virtio'/>
<boot order='1'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
</disk>
<disk type='file' device='cdrom'>
<driver name='qemu' type='raw'/>
<source file='/mnt/user/isos/Win10_1809Oct_EnglishInternational_x64.iso'/>
<target dev='hda' bus='ide'/>
<readonly/>
<boot order='2'/>
<address type='drive' controller='0' bus='0' target='0' unit='0'/>
</disk>
<disk type='file' device='cdrom'>
<driver name='qemu' type='raw'/>
<source file='/mnt/user/isos/virtio-win-0.1.160-1.iso'/>
<target dev='hdb' bus='ide'/>
<readonly/>
<address type='drive' controller='0' bus='0' target='0' unit='1'/>
</disk>
<controller type='usb' index='0' model='ich9-ehci1'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x7'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci1'>
<master startport='0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0' multifunction='on'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci2'>
<master startport='2'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x1'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci3'>
<master startport='4'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x2'/>
</controller>
<controller type='pci' index='0' model='pci-root'/>
<controller type='ide' index='0'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
</controller>
<controller type='virtio-serial' index='0'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
</controller>
<interface type='bridge'>
<mac address='52:54:00:50:a8:3f'/>
<source bridge='br0'/>
<model type='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
</interface>
<serial type='pty'>
<target type='isa-serial' port='0'>
<model name='isa-serial'/>
</target>
</serial>
<console type='pty'>
<target type='serial' port='0'/>
</console>
<channel type='unix'>
<target type='virtio' name='org.qemu.guest_agent.0'/>
<address type='virtio-serial' controller='0' bus='0' port='1'/>
</channel>
<input type='tablet' bus='usb'>
<address type='usb' bus='0' port='1'/>
</input>
<input type='mouse' bus='ps2'/>
<input type='keyboard' bus='ps2'/>
<hostdev mode='subsystem' type='pci' managed='yes'>
<driver name='vfio'/>
<source>
<address domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
</source>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
</hostdev>
<memballoon model='none'/>
</devices>
</domain>