I don't think this was the issue. Restarting the computer and Illustrator fixed the problem.
Also toggling Show/Hide Edges doesn't replicate this issue for me.

It feels like Cmd+H was pressed unintentionally, and Illustrator stopped showing edges to you. Please try to enable them back, with Ctrl+H or via View > Show Edges.
Does it help?

When moving shapes around the artboard, the bounding box disappears. This makes positioning objects with no stroke or fill almost impossible.

Video attached showing behaviour.

I am using Adobe Illustrator for over 10 years and this is such a flaw. I mean I can get used to it, but if another program as Affinity Designer has guides, I will switch soon to that program. Please fix this! Guides are no where to be found while moving paths, shapes etc. this is not good.

I'm surprised there are not more votes on this! please fix

THIS PROBLEM IS DRIVING ME CRAZY.

In order to be able to see my guides as I move them, I must have Real-Time Drawing and Editing off. Surely, this can be fixed so we can take advantage of this feature but still be able to see where we are moving our guides.

@George Williamson, telling people to "get better hardware" is not the solution. That's utterly ridiculous! I have a tower PC with three Nvidia 2080Ti's and the problem affects me just as much as anyone else.

Neither is the solution to "uncheck the Realtime drawing". This is a 'hack' that many people have suggested but fail to realize that in doing so they are disabling a feature that they are paying for. The reason we pay (pricey) subscriptions is to fund the continuous development and improvements. Switching new features off just to save one of the oldest and most fundamental features (guides) is ridiculous.

The Solution that we all need to PUSH adobe in to action is.... "fix the buggy software" !!

Well if it worked before they broke it, "average hardware" seems a bad argument to me. For example my iMac 2019 should be powerful enough to handle this (but I have this bug, too - also on other computers). It is just one of many bugs in Illustrator and if it does not appear on your machine, you are lucky. But don’t tell people to buy new hardware, because Adobe broke their software....

You can Solve it by Doing the following steps:
Go to Illustrator Preferences > Performance and un-check "Real-Time Drawing and Editing."
This happens because of average hardware. Get a better laptop I would say.
Check Something from here: https://expertratings.net/best-laptop-for-adobe-illustrator/

And today we've reached the v.25.2.2 and still haven't a fix for this bug!!!
Is it a joke?? The only solution at the moment is disable the real time preview but is a pain...

You mean a guide? Known bug. Disable GPU for now or try to drag a guide using Direct Selection tool.

I vote for a better fix to this, meantime however, there is another useful work around here:
https://dviz.me/guides-disappear-1c688
Especially useful for me is this little trick found way down in that post: place guides on a separate layer, and turn off "preview" for that layer.

I hate this! Why would anyone want their guides to disappear when repositioning them?? Big thanks to Anonymous for sharing how to turn this off. Very dumb.

Guides disappear when I drag them to reposition. They work fine when I drag one out from the ruler, but if I try to reposition, they are not visible when I drag and they appear when I release.

Unchecking Real-Time Drawing is just a poor workaround and not a fix! Adobe introduced even more GPU related Bugs with Illustrator 2021! Come on Adobe, don’t think of adding useless new features - FIX the existing ones, that we need to use every day!

Problem solved!
Go to Illustrator Preferences > Performance and un-check "Real-Time Drawing and Editing."
See attachement.

Problem solved!
Go to Illustrator Preferences > Performance and un-check "Real-Time Drawing and Editing."

Same issue here. Disabling GPU seems to solve. Is there a list of specific GPUs that seem to play nicer with Adobe going into future releases?

Known bug.
Vote here: https://illustrator.uservoice.com/forums/601447-illustrator-desktop-bugs/suggestions/39740689-realtime-preview-makes-rulers-and-objects-disappea
As a temp solution, disable GPU preview.

Please merge.