Do all of these have the same issue, across the board in all 2.50.x releases; or is only one of these that has this issue in all 2.50.x releases?
James, i do wish that you would be more specific, and detailed. What quest files you tested in each version, and what the result was for each, in each ZC/ZQuest version, linking to the quest files. This level of compatibility is a very marginal concern for most people, and getting it to work properly, or figuring out the causes will take considerable time and effort. As such, it would be extremely useful not to need to duplicate every test from here, that you have already done.
In general, the best way to report this is something like this:
Quest File (made in specify version of ZC)
Test Results for 2.50.0: Quest does this; works right; has these issues.
Test Results for 2.50.1: Quest does this; works right; has these issues.
Test Results for 2.50.2: Quest does this; works right; has these issues.
Test Results for 2.50.3rc1: Quest does this; works right; has these issues.
Test Results for 2.53.0 Beta n: Quest does this; works right; has these issues.
If you also feel like testing it in 2.10, you can provide those results, but they may not be helpful at this stage.
The more detailed your reports are, the easier it will be for us to (1) schedule a series of our own tests, (2) determine a point at which this issue first occurred. (3) examine the issue and search for a root cause, (4) consider a potential fix implementation.
If none of these quest load tiles properly in any 2.50.x version, then it is possible that the tile loading mechanism for them is simply not properly implemented at all. If it only affects some quests, then it is a much stranger issue, and will be harder to diagnose.
Something that is not clear to me is if this is a ZQuest issue (tile editor), or a an issue with Zelda Classic reading combos. ZC does not 'read tiles', it reads combos which store tile data. Where you are encountering the issue, and precise details that explain what is happening (screenshots would be nice) would be quite handy to have.
I can delve into the 1.50 tiles in ZQ, and the 1.50 combo reading in ZC, but it's hard to say how helpful that will be, which is why I asked if you can find a 2.50.x version in which this worked, so that if it broke in recent history, we can find a cause. If it broke in 2.10 or earlier--oh bio--this will be a bastard to correct.