When using WMI discovery the asset type is changed from desktop,laptop, tablet etc to Hardware even though the "do not overwrite value" box is checked.. This is highly annoying !
Don't edit the assets, Go to Settings - Assets - Manufacturers & Models - Then search for Dell, go to the Model editor tab, then for each model change the type to desktop / laptop etc. Also for the attribute mappings also tick "do not overwrite existing value" for model. Then try the sync again.
That's awesome thanks!