It’s pretty common for recently fixed rabbits to lose their litterbox habits. She may need to be re-taught. It sounds like she also might not like the box that you’re using. Have you tried other boxes, possibly one with lower sides?

She also may not like the location. If she’s picking another corner to go to the bathroom in more regularly, try putting the box in that corner instead. Are you putting hay in the box and/or in a rack, basket, or box where she can munch while she goes? Hay will attract a bun to the box. You can also put a few tasty, healthy greens that she likes inside the box so that she’s more tempted to go fully into the box.

If you feel it’s necessary to start the whole rigmarole of training again, what you can do is make her area a bit smaller, so that she has less of other areas to go, but make sure she’s also getting a lot of exercise and out time, and put her in this smaller area at night when it’s time to sleep. This should make her adjust to using the box more quickly after a few weeks. Then you can re-expand her area.

No matter what you decide to do, it will probably take a few weeks of adjusting for her to come back to her litterbox skills, but more than likely she eventually will.

Haha, her moving the box out of the corner suggests to me that she either doesn’t LIKE the box, or that she doesn’t understand that she’s supposed to to INSIDE of the box. Fixing ultimately does change some of their behavior and attitudes, so this is probably just her deciding she doesnt like or understand the box anymore. Re-training her will probably help with this.