I updated Questie to 7.1.2 in Wrath Classic and can no longer resize the quest tracker window. The change log mentioned changes to the default tracker growth functionality, so I imagine it is related to that.

Same happened to me, v7.1.2 as well.

This has been an issue for me for a week. For me, the backdrop grows to the right. So if I line my tracker to the right of my screen it will progressively grow to the right and move the tracker to to center. There is no way to resize the tracker backdrop. The only way to fix, albeit temporarily, is to reset the tracker position then reload, but the tracker immediately starts growing again after a reset and reload. I have no idea what is triggering is to grow. If I line my tracker to the left, the backdrop still grows, but the tracker doesn't move because it is growing to the right.

i fixxed this disabling the addon "Capping" and using /reload

It keeps doing this re-size thing and everything under the invisible box isn't clickable. Really fucks with the UI.

what debug info under the advanced tab in the addon, would you need, and how would I get it to you?

Mine is also growing to the right, I use reload to reset it, but it is annoying. Once I have a full quest log, and it grows right, I can not target or do any sort of interaction with npc in game, until i reload.

For me I can't even resize it in WOTLK at all, no mods aside from questie.