What you were expecting to happen, and what actually happened:
Neither of those backgrounds are correct for either Delve. I think that’s Whitehelm’s background, but I think I’ve saw Leonis Empire, on the first occasion.
How often does this happen? When did it begin happening?
I first noticed this yesterday. Seems to happen occasionally, possibly on first restarting the game after reset. Note that I’ve been playing daily delves for months, and this problem really did start this week (either that, or I just managed to avoid it in the past).
Steps to make it happen again
You tell me.
You clearly have some sort of asset indexing and/or caching bug, as indicated by the incorrect labelling of game loading images, particularly just after an update. As mentioned elsewhere, it also affects the troops shown on battle loading screens.
I’ve now provided proof of all three variations. At the very least, I expect to see them all in the Known Bugs List.
The trouble is, bugs you leave behind often come back to bite you.
For example, I’m almost certain that the new GW scoring bug is related to previous GW bugs. However, the entire GW system has not been revisited for at least 3 years, except for tiny band-aids.
The real issue is that Inf+2 don’t know how to schedule concurrent work, nor make time for constant, retroactive improvement. To be fair, MOST software developers don’t know how to do this!
Ultimately, the presumption that “new content is king” is utter nonsense. If version 6 had been delayed by 6 months, not one player would have noticed – and nor would the accountants. Conversely, every player would notice if the Guild Wars user interface were finally fixed – and that’s just one of hundreds of examples we’ve reported over the years.
ADDITIONAL: To hear from one of the very few studio heads in the world that absolutely knows what he’s doing, look up the “Play, Watch, Listen” YouTube podcast: every word Mike Bithell speaks about game development is absolute gold (his most famous game is “Tomas was Alone”).