Thats good news the problem many be similar to this problem that happened to me as well same problem with memory calculation.
My way around this is to use an Android mobile phone (example old Samsung Galaxy 10)
Load Fortnite onto phone, open lobby on phone select on UEFN on the dots Launch …
select Connect Console
Click Launch and the game starts on phone, Click red Stop Game then select Memory Calculation, which happens on phone and transfers to UEFN about about 3 minutes.
This works on any console device Xbox One , Nintendo Switch 1 etc
Well at least its sort of working 
most of the time