I'm guessing that the Legion ring needs to be specifically programmed to a time period to be used to go to that period. The last time it was used was from the 31st century so I too assumed that Lois went to the Legion period not a year. Dr. Hamilton did point out that there was a temporal anomaly, a rip in the fabric is how he put it to Chloe. Maybe this has something to do with Lois being tossed into the future. What I hope is also explained is why she can't remember anything . Most likely her memories were altered or blocked.