Try with converting the data info ID to a Long. This worked for me (slightly different script as I was doing it in 7.9, but looks like this is the issue you’re having
from com.inductiveautomation.ignition.gateway import IgnitionGateway
from java.lang import Long
gateway = IgnitionGateway.get()
histMngr = gateway.getHistoryManager()
stores = histMngr.getStores(None) #none = getAll
for store in stores:
qdataInfo = histMngr.getQuarantinedDataInfo(store)
ids = [Long(x.getId()) for x in qdataInfo]
if ids:
histMngr.unquarantineData(store,ids)