|Well done for the data safeguarding; sadyl many don't really think about it bother (until it's too late).|
Does the drive show in the bios?
If you try the ubuntu boot does it show up there?
A suggestion for the future... arather than a factory reset routine with the assorted "globe trotting laptops" consider re-imaging them when required?
Set each one up as you wish it to be - OS settings and apps. Possibly they all use the same OS and apps etc. so likely one or two mages may be all you need?
Then having safeguarded data when situation arirses, simply re-apply image afresh?
Also regularly run (install on each latop) a few safe cleaners... There are are several well recommended here. They may help reduce much of the clutter to which you refer..
Also keep a note of assorted OS and apps keys for each laptop; may be useful to have at time in the future...