I honestly can't say I've tried it on Frixion pen marks but hydrogen peroxide has saved me on many other problems.
Good luck on your quest...I feel your pain!

Be careful using dishwasher compound -- it may contain bleach. It may ruin your quilt.

Windex is also an option for removing some kinds of marker stains.

I use a product called SoilLove to remove stains that other commercial products can't touch. It's especially good on organic things like baby food, other less pleasant stains, etc. You can buy it online.

Did you try hydrogen peroxide?

Note: I would NOT layer these attempts on top of each other since one may react with the other.

I would stay away from ShoutOut and Woollite since I think they contain bleach-like products. (I've had things fade or develop holes later on or after repeated use.)

Good Luck!

Oh my, you poor dear. If the quilt is for yourself, just love it and enjoy the beautiful quilting you have done it and remember, lesson learned.

I can feel for you. I used a blue chalk marker on some embroideries years ago. Put everything away due to moving and finally after so many years started unpacking some of the totes to see what was in them and found these embroideries with the blue markings still there. I serged the edges and put them thru the washing cycle to see if the marks would come out, even sprayed them with Spray & Wash. Some of the marks came out but most did not. Nowadays I put my marks just at the edge of the fabric to hoop it so it will either be hidden in the seam or chopped off. Have learned the hard way. I'm sure if I had removed the marks earlier I wouldn't have had this issue but time in storage made its ugly mark. Lesson learned.

Hope you find a way to remove them after all that work you put into it.

zozee: care to share the recipe for the amish color catcher

Puma, I'm having trouble copying the link on my phone.

Go go up yo the search bar and type in Recipe to Keep Colirs from Running." I posted it in the Links and Resources section 3 years ago. Others asked questions that you might want to read there as well.