With this patch, I can no longer click on people in my raid frames, including my unit frame, if I hold down my modifiers (shift, ctrl, alt).
This is a huge bug for healers. I personally rely on pre-selecting people I am going to heal between GCD. It’s unplayable right now 
There is also a US report:
If you use the Clique addon you will have to tick the option off to trigger on Key Down.
It is an awfull lots of clicks to turn it off but here you go: Opening Clique → Options → Clique Options, Select General Options and tick off “Trigger Bindings on the Down portion of the click or keypress”
Other addons might have a similar option (you don’t mention what addons you are using or even what version of the game you are playing)
Thank you for your input. Perhaps it could help someone who uses Clique.
I am not using any addons for my raid or unit frames. The issue also persists if I disable all addons.
Even in the topic I linked, some people do not have this bug if they use ElvUI or EllesmereUI.
Currently, some portion of this bug was reported on CS Discord, however, it doesn’t mention modifiers. They suggested resetting keybindings or Click Casting keybindings, which didn’t work.
Even though that wouldn’t be the first time I installed an addon to solve a bug that Blizzy only took 4 patches to solve (hello to Auto Loot). Raid frames addons are not something I ever liked. That would be ridiculous if I had to install yet another addon to solve something Blizz broke yesterday 
Hey all,
I can confirm that our developers are currently investigating this issue. As a temporary fix, you can use the “Reset to Default” option in Menu > Options > Keybindings > Click Casting to resolve this issue. Alternatively, you can try and see if you can change your current bindings in this same window.
You can also find more information about known issues and their resolution on our Blizzard Support Discord server.
Bug fixes are often posted in our Hotfixes and Updates blogs, in the News section of the site. If you encounter another bug in-game, please report it to them, and they will be able to review it for you.
Sorry for the inconvenience, and thank you for your patience!
I suspect the root cause is the trigger now being fired as soon a key is pressed, and not when it is released (which was standard earlier): so if you press your modifier 0.01 seconds after pressing the key or mouse button then the spell is already fired and the modifier is unused.
You can verify if this is actually the issue by pressing and holding a modifier and _then_ cast your heal / whatever: if it works then you at least know why it fails.
And if that is indeed the case I would try to see if there is some way to change WoW back to use OnkeyUp rather than OnKeyDown - that is what I did with Clique.
Edit: Aah, a blue ninja’ed my post 
Hey, thank you for your answer.
As I mentioned above, I saw your report on the CS Discord, and the temporary fix doesn’t seem to be working.
I have just tried to do it again, and I re-bound all my keybindings as well.
Hopefully, it will be fixed soon.
Make a macro “/target” then open “Click Casting” settings Add a new shortcut with the new macro then assign “shift + clic” Add a new shortcut with the new macro then assign “alt + clic”
This is my temporary work around for this, and this works!!
Example: https ://i .gyazo.com/feb6f19111ac1ef9245167cb031ab3fb.png
(remove space in link)
Hey,
Thank you for your answer. This feels like a proper temporary fix.
It also worked for me.
I saw a similar fix in this post, too:
Hey forum moderator. I see that this issue is still persisting.
The click casting fix does not fix it. removing addons does not work. reinstalling game does not work. fiddling with other settings does not work. Macroing workarounds does not work because it’ll still act like a mix of stickytargeting and selfcasting instead. The only thing that functions is an addon which soomeone release some 14minutes after the patch went out.
But the main reason I’m replying here is because the bug report was altered on discord and no longer represent the error at hand. It’s ONLY an “error with targeting while holding ANY of the modifiers”. nothing more. nothing less.
I haven’t healed any raid on my healers, nor done a single arena match or a key for 8 days now, soon to be 10 days, given that it’s most likely won’t be fixed over this weekend as well 