We need clues, pelase.

What are the directions that you're following?

Also,
What are the light conditions? (likely needs more light.)
How much water do you give it?
And how often do you water it?
What is the prevailing indoor temperature?
Day temp?
Night temp?

Often these are grown in near-tropical conditions with very high humidity, then mass shipped up to our home centers here in heating climates with central heating and low humidity; it's a real shock to them.
Sometimes it's so bad that these must loose all the high-humidity-created leaves before it stabilizes. It shouldn't be happening fast though.
Rubber plants like constant moisture in fertile soils that have good drainage. Right now it should have very high light that is not direct sunlight unless early or late in the day. Keep it away from heater ducts, fireplaces, etc. A less heated room with bright light will have higher humidity.
- Tom

Yes, houseplants go through something like transplant shock when moved to a new home. And one must assume that they didn't get the best of care while at the big box store and while being transported from greenhouse to store. So poor thing's just in shock right now.

I'm not big on houseplants but I have found that most houseplants recommended for indirect light, need more direct window light here especially in winter because there's so little sun to start with. I have a fancy begonia in a southern window, for instance, and another one in a west window. Even in summer they don't burn.

It is true that houseplants in Western WA and OR require more light than they do in the rest of the country. Our clouds and rain aren't taken into account when tags or books are written with light recommendations.

Thank you all for the info! It is much appreciated.

A bunch of leaves all falling off at once is a cultural problem like too much or not enough water, or a too cold and damp growing room. Merely moving the plant from one normal location to another will not produce such a dramatic response, except perhaps in the case of weeping fig trees. These are notorious for this and are just about the only kind of indoor plant I have had behave in this manner.

That weeping fig is a good example, since it's very closely related to Leena's fig tree (same genus). The other figs (incl her Ficus elastica) act in similar way, being generally just barely suitable as houseplants.
I really think this is a classic case of outdoors-in shock, being mostly humidity but also probably light & water. The home center was just a temporary stop, not where the leaves were developed.
I've found that most tropical plants can not "convert" a high-humidity leaf to a low-humidity environment when you bring them indoors, like they usually can convert a leaf to higher light if done gradually. Usually they just have to shed all the outdoor created leaves, maybe over a year-long period, especially a finnicky genus like Ficus.
Keep it perfectly watered, wash the dust & bugs off the leaves every time you water for awhile, and kick up the light (maybe an extra fluorescent above it, in addition to a bright window?). Focus on the new leaves being produced. If those are healthy & coming quickly then you'll do fine.
- Tom