Catholic University officials had said the dress went missing for decades after being given to Hartke, then head of the drama department.
The dress was rediscovered at the school last year in a shoebox during preparations for a renovation.
The dramatic story of a costume from The Wizard of Oz thought lost for decades went through another plot twist on Monday, when a judge blocked its planned sale at auction.
Auctioneer Bonhams listed a pre-sale estimate of $800,000 to $1.2m for the dress before it was withdrawn.