Follow up: First, for the next couple of weeks she'll need only easily dissolved feeds as you're giving her: crumbles and water.
Something is causing her system to be slow. You've ruled out a blockage in her crop last night through the flush. So now you know it's systemic (unless there's blockage somewhere lower along her system, including tumors, inflammation, worms, etc - we can't see that yet so let's just go systemic).
First, she'll need a digestive tract tune-up which will hopefully get her system going. For the sludge of feed sitting too long in her crop and digestive tract, you'll use organic apple cider vinegar in her water at a rate of 1 teaspoon OACV per gallon of water. Use this as her sole source of water for at least a week. Then every other day for 2 weeks.
Using organic, not regular, means that the vinegar still has the lactobacilli in it that created the vinegar. It's the "mother" of the vinegar - the gunk in the bottom and in the vinegar itself. More on why that's important below. Additionally, the pH of that solution of vinegar to water will help to correct the pH of the digestive tract of your bird so it's friendly for good bacteria, and unfriendly for pathogens like bad bacteria, and most importantly fungi (commonly called 'yeast').
Yeast (fungal) issues and a lack of healthy gut bacteria are a major cause of crop stasis (slow crop). The reason is that the bacteria in the digestive tract play a part in producing enzymes that help make food absorbable so that it can be digested and not just sit in the digestive tract, creating toxins and backing food up. The same bacteria also compete for the digestive tract with the bad stuff. Through competition, they keep blooms of pathogens away in a healthy bird. There are already pathogens in all our birds - but the bacteria are what keep them in small non-harmful numbers.
Anything can cause these bacteria to die back. Stress, medication, change in diet, illness, etc. So through the use of probiotics we replace them.
Probiotics are a non-medicinal carrier of live bacteria in a media in which they can stay alive til they're able to get into the gut and colonize it. Surprisingly, yogurt is a probiotic. The dairy product is the carrier, and it's filled with live lactobacilli, specifically Lactobacillus acidophilis which is the one that colonizes the digestive tract best.
If you're not using an antibiotic that ends in -mycin or -cycline, you can use plain unflavored yogurt as a probiotic for your bird. Other alternatives (which you CAN use while medicating) are acidophillis capsules/tablets from the vitamin section of the grocer/druggist, or a prepared live-bacteria probiotic like Probios dispersible powder from the feed store, or another brand. When buying a livestock probiotic, be sure and read the label for something saying "CFU" followed by numbers. This shows how many live 'colony forming units" are in the probiotic. That means there's actually live bacteria, not just "products of fermentation" . There can be fermentation products, but the product must contain CFU's of bacteria.
If you use yogurt, 1 tablespoon is good for an adult, 1 teaspoon for a small pullet. Most eat it straight, but if they don't then you can mix it with a little water and use that mixed in a few crumbles and let them absorb for 10 minutes - then feed to her. mixing a little yolk of a boiled egg (no whites please) might also tempt her, and it dissolves easily in water so her system doesn't have to do any work.
So, in short, let's see if we can get the digestive tract running at full speed, kill off some possible yeast in the crop, and get this crop to start emptying:
yogurt or another probiotic: daily for at least one week - every other day 2 weeks thereafter.
OACV: daily for at least one week - every other day 2 weeks afterwards
Easily dissolved feeds: her crumbles, water.
If your crop issue is a stronger yeast (fungal candida) infection, then this will at least help and not harm.
Then after the week - if she's not better, reevaluate. You might have to reflush her crop using the baking-soda method that Glenda Heywood posts here on the board. The baking-soda helps to make the digestive tract cleaner, too. Let us know if you need that post.
Please let us know how she's doing. Keep feed in front of her at all times to keep her from binging. If you have time, try to get her interested in food several times a day. Offering a wet mash (with the oacv water as the water mixed in with the crumbles) throughout the day might also help if you're willing and have the time to do it.