RB63 Sounds like a bug yeah. Good job narrowing it down.
I would initially report it on the GivEnergy forums - and perhaps the GivEnergy Owners Facebook group, there's quite a few Giv employees active on both.
Worth attaching the log in question, and highlighting that settings are all the same, but you need to toggle Eco on and back off for them to have effect.
Are you on the latest firmware? That's probably their first question. 😉
And I guess one thing to try would be to reproduce the issue via the Giv app if at all possible, perhaps update settings in the same order?