Photoshop version 24.0.0 - but I started noticing this bug a version or two prior, and just hoped it would get resolved by a coming update. So far, it hasn't.
How it should work:
As you know, documents with artboards use guides both at the artboard level and canvas level, and the two kinds of guide can be toggled on/off via the View -> Guides menu. Until recently, the way these guides have always worked was that whichever artboard was active (selected in the Layers pallet) would receive & hold any new guides being created by drag/dropping them from the rulers. When that artboard goes out of focus (is NOT selected in the Layers pallet) the arboard guides are hidden, and only the newly-selected artboard and/or canvas guides are then visible. When you save/closed and reopened a document, those guides remained attached to the target they were dropped on, either artboard or canvas. And if you wanted to delete a guide, you could drag it back to a ruler—it did not remain selected and vulnerable to be deleted via the backspace or delete key.
The current bug:
As of version 24 (or 1-2 minor updates prior), artboard guides no longer stay attached to the appropriate artboard when you switch focus to a new artboard or save/close and reopen a document. Close and re-open the file, and you may find that about half the artboard guides have either become anchored to another artboard or converted to canvas guides. Also when switching focus between artboards, all the new artboard's guides do not always become visible until you drag one of the visible guides or drag a new one from a ruler. It's honestly hard to tell which guides Photoshop is treating as canvas guides and which it is treating as artboard guides.
Finally, the guides now stay active/selected after you drag and drop them, which means unless you click somewhere else to de-select it before hitting the delete key, the guide gets deleted. In my workflow, I frequently delete a layer from the Layers pallet after dragging a guide. There's no reason I can see for leaving the guide selected (you can't edit its position without using the right-click menu, or do anything other than delete it—which could be done by dragging it to a ruler), so leaving it selected just gets in the way. Would love to see this revert to the previous behavior.
I can confirm that the preference to show inactive artboard guides is not checked, so that shouldn't be part of the problem.
Happy to post other details if it would help. Thanks!
There has been an intentional change to allow you to select and edit individual and multiple guides. When you select and move a guide, it remains selected, hence it's deleted if the Delete key is pressed.
I'm not able to repro the issue with guides disappearing or not being attached to the right Artboard. A screen recording demonstrating your issue and/or sharing the file you're having trouble with may help (post a URL to the file using CC files or dropbox, or something similar).
Senior Product Manager - Customer Advocacy - Digital Imaging