I don't get why Dish hasn't figured it out. Directv added it back in august.
It actually might NOT be E*'s fault, but the fault of the station(s) itself - the way the rules are, is for the LRF (Local Receive Facility) that is designated for each DMA, it is up to each, individual station to get a "quality signal" to that said facility. If the station's OTA signal cannot be received at a certain threshold, then it is up to that said station THEMSELVES, to get it there somehow, AND at their expense! (usually via a fiber feed) Assuming that E* & D* in this market have LRF's in different facilities, it might appear that the local station is having the issue with whatever fiber provider they were using, to get it back up & running.
Or...it's also possible that the station looked at what they were paying to get the signal to DISH, ran the numbers & considered that maybe DISH is loosing so many subs...as well as how funding cuts is affecting most PBS stations, it wasn't worth the recurring cost to get it back up on DISH. Maybe you should reach out to the station & see if they will even give you an answer as to why they're not coming back on E*. (see my issue below...)
We have the very same issue in my market, but it's with DirecTV NO longer carrying 2 of our 3 PBS stations for years...while DISH has continued to carry all of them with no issues. Right after AT&T took over DirecTV, they decided to move their designated LRF for our market, 30 miles east from our local FOX TV studios in Springfield to Decatur in the AT&T local office. (Also keep in mind, DISH's LRF is ALSO located in Decatur & has been there since day 1) I'll also mention WSEC's tower is 35+ miles west of Springfield.
When this move happened, we immediately lost WEIU-51 out of Charleston, due to it being too far south to even think of getting a quality signal OTA either place; it has always had a fiber feed to both E* & D* LRF's. We also lost WSEC-14 out of Jacksonville, because (supposedly) D* claims their OTA signal was under the quality threshold to be carried; keep in mind though, that E* has always carried it via OTA & doesn't seem to have any issues with "signal quality". D* briefly added it back for a few days, then within a week dropped it, again claiming "signal quality issues" with WSEC's transition to a new OTA frequency during the last repack. The thing is, WSEC-14 IS actually considered our primary PBS for our (western) part of our DMA; EVERY cable system in our area has always carried it w/out issue.
I've actually reached out to WSEC several times & all they have ever told me is, "we'll look into this". After thinking about it, I believe with with being forced to pay for a fiber connection, & with all the funding cuts to PBS, WSEC decided it wasn't worth it being put back up on D*; they were also dropped from AT&T U-verse at the same time the LRF moved. I never reached out to WEIU, but I imagine it's probably the same story, particularly since they cover the smallest portion of our DMA. (though again, the don't seem to have an issue paying it for carriage on E*...)