Very likely just what I call MIS - Moving Indoor Shock. It happens to many of my plants when I bring them in. For example, I have two tropical (indoor) Hibiscus that drop ~ 90 % of their leaves when I bring them in. It is scary fer sure, but at least with these two plants, I have learned from experience they will recover in a month or so.
Also keep in mind that some plants like to go at least partially dormant this time of year.
Not sure what type Ivy you have, but Aglaonema is often treated as a houseplant year round. Same for many Ivy.
For my plants that I bring in, I try to give them as much indirect light as possible and/or East or West window light.
And I am careful about watering.
