Simply put .... your answer is in the previous posts.

Agree, that's pretty much the usual shrinkage with 100% cottons ... I don't see the problem ???

That's too bad that happened, puts a damper on your plan for the backing.

Actually I DID read many of the previous posts ... I guess we can all "agree to disagree" !

I've been quilting for 25 years and all I can add is, when you prewash fabrics and wash your quilts in HOT water and DRY on HOT, they WILL shrink, they WILL wear, and most fabrics WILL lose color prematurely. Drying a quilt in the dryer WILL shorten its life considerably ...
There's NO other result for 100% cottons ... so why would quilters who do this expect anything different ???

The reasons have been stated. Good ones at that.
And they totally are in line with what you have stated.
What some see as positives ... no doubt you see as negatives!! :D

The excessive rate of shrinkage that the OP got with this particular fabric is not usual, not at all, even using hot water and a hot drying temp. Since you obviously have no experience using those conditions, there is no reason for you to be so adamant about the results obtained.

Sorry to ruffle anyone's feathers ... (I think I remember now WHY I don't post as much here anymore ... !!)
I thought the intent of this board was to share observations, tips and opinions ... guess I'm wrong !

While I've never washed & dried my fabrics or quilts on HOT settings ... over the years, I HAVE SEEN the unhappy results of quite a few who DID ...

We can expect different results because of the advance in the chemical dyes over the last 25 years. Some like blue jeans are made to fade; others can be washed in hot, dried on hot twice a week and still look brand new. That's why companies spend so much money on research and graduating chemists can still find jobs that aren't in cosmetics and fertilizer fields, for just 2 examples. We've come a long way, baby! They still need to conquor red and black. LOL!

Oh no!! So sorry that happened to you with such expensive fabric!

Ouch! that hurts. I don't always wash my fabric. It depends on what it will be used for. . . Wall hanging. . No. Quilt that will be washed. . Yes! and in the way I think it may be washed and dried. You were fortunate to discover this flaw BEFORE you put hours of your time into the quilt. I think I would have to have a serious chat with Henry regarding his product.
By the way, for what it's worth, I seem to live my life in plan B.