When did she last poop?
I don't think it's an impaction at all, I think it's the MBD progressing and getting worse due to inadequate UVB exposure. You cannot mount a T8 UVB tube, not any brand, on top of a mesh lid, it is blocking at least 40% of the already weak
UVB light. Honestly, a dragon with progressive MBD should have a T5 strength UVB tube, but the Reptisun 10.0 T8 UVB tube will be fine as long as it is mounted under the mesh lid UNOBSTRUCTED by anything, and is within 6" of her main basking spot.
You need to poke 4 holes in the mesh lid, with a pair of scissors or a utility knife and use those really wide, long, plastic Zip Ties (you can buy these in packs of 10 at any Walmart, DollarTree, Lowes, Home Depot) to strap the entire tube fixture to the underside of the mesh lid, MAKING SURE THAT YOU HAVE THE UVB TUBE MOUNTED RIGHT ALONGSIDE THE BASKING LIGHT AND THAT BOTH LIGHTS ARE LOCATED IN THE HOT SIDE OF THE TANK AND THAT BOTH ARE DIRECTLY OVER HER BASKING SPOT. This is extremely important, you're trying to replicate natural sunlight directly overtop of her Basking Spot in the Hot Side of her enclosure, and you do this by putting the UVB tube (I'm assuming it's an 18" Reptisun 10.0 T8 so it will be easy to mount under the mesh and CENTERED over the middle of the Hot Side, with the Basking Spot/Platform directly underneath it and the Basking Light) and the Basking Light right next to each other, making sure the UVB tube is centered over the Hot Side with the Basking Spot right underneath it, so that she gets both lights at the same time while basking.
You also must make absolutely sure that after you get the UVB tube strapped to the underside of the mesh lid and centered in the Hot Side with the Basking Light right next to it, that whatever you use as her Basking Spot/Platform is high enough to be within at least 6" of the unobstructed tube.This is crucial, and you are not doing anything to reverse her MBD at all without getting her lights mounted correctly, and making sure that both lights are on for at least 14 hours every day. Without doing this she is not absorbing ANY of the calcium you are giving her or that she is eating in her food, and her MBD is just getting worse and worse.
That's the bottom line: A T8 strength UVB tube just isn't strong enough to be blocked by anything like a mesh lid or to be any further away from your dragon while she is basking than 6". Also very important, AFTER YOU GET HER LIGHTING SET UP PROPERLY, please double check her Basking Spot Surface Temperature again using either a Digital Thermometer with a Probe on a Wire or a Temperature Gun (NO stick-on thermometers, you can't measure her Basking Spot Surface Temp with a stick-on thermometer), and make sure it is between 105-110 degress, as this is also extremely important for a dragon with MBD to be able to properly digest their food and be able to absorb and process the nutrition from it, including the calcium.
