I am having the exact problem with the XTOL produced by that Chinese company, the one contracted to do XTOL with Alaris. The descriptions of the problems with Eco pro and underdevelopment are precisely what I am experiencing with the new XTOL. I've used the original Kodak manufactured XTOL for about 20 years and assumed the new XTOL was a drop-in replacement. It is not. It fails to give me expected results in exactly the same way that Eco pro does. Could it be that both are manufactured by the same company?
So, I started developing with EcoPro right after this thread was started. I've been through precisely one bag of the stuff.
I've started with xtol times from massive dev chart on every stock I've used so far, and just followed Kodak instructions (adding time after 5 rolls, after 10 rolls, tossing it and starting a new liter after 15 rolls) and I never feel like anything is underdeveloped. Even diluting 1:1. But I haven't used old-schoold Kodak Xtol so I can't call it a direct comparison.
Maybe they're made by the same company. Maybe whatever the issue seen above was, it's the same. That said, I bought my EcoPro around September last year, and OP said he had used a previous batch with no such issues, so.... I don't think we can conclude anything. But if the same manufacturer is doing it, maybe there was a batch not quite to spec. I guess we can collect people's experiences here and speculate if more people see the issue.
Personally, I'm just going to choose my next bag (I'm half way through the last one) based on the same criteria I chose EcoPro in the first place: what's in stock. I'll keep on trucking like I have been, starting with the times I like and keeping my fingers crossed. Maybe I'll start with a roll I'm not really worried about.