Lightroom Migrate failure

Hi,

Having spent hours running the migration of over 45,000 photos into Lightroom in Cloud from Lightroom Classic - the program exited after running for hous (only noticed when returned to check on it's progress) and I now find when I fire up Lightroom there are only just over 9,000 photos out of the 45,000 present ? Absolutely loads of local free disk space and upgraded Cloud to 1TB before starting for this very purpose. Bearing in mind it says you can only Migrate once - what do I do now ? Also where is any log to tell me why it failed to complete ? I've now doubled my monthly plan charge to no avail.  Thanks Des