I have no luck with Photoshop-HELP PLEASE

I've recently watched a YouTube tutorial on how to add a drop shadow border to my images. All has been good for a couple of days but trying to do this today is impossible. My workflow goes like this...
Edit my RAW image in LR
Click the photo tab-Edit in-Photoshop CC 2019
Photo then opens up in PS.
I should then be able to click on the image layer and duplicate the layer....but it wont let me!!
YouTube advice says that its something to do with the image mode.
It advises to click on the image tab and then the mode tab, and change to RGB.

However, mode is grayed out and I cant select anything. Pretty much all commands are grayed out.

WTF?? ARRRGGGGHHHH.

Try saving the image from LR as an 8-bit TIFF then open that in Photoshop

Apparently a known problem which can happen if PS is opened from Lightroom Classic CC, although it’s not happened to me.
Try opening Photoshop before processing in Lightroom.

By opening straight in PS then yes it works thanks. It worked 2 days ago but now no. I wonder if its because I have updated to PS 2019 and LR is still CC Classic??

I have just had the same problem. I bought a new PC and installed LR and PS. When using the 'Edit in Photoshop' from LR option, it opens up PS, but all the PS menu's are greyed out and there is very limited functionality.

As Keith B states........the solution is to open up Photoshop BEFORE you select the 'Edit in...' command from LR (ie. have PS running in the background). Spent half a day trying to work out why this is happening, but It looks like it is a bug. The funny thing was, everything worked OK on my old PC

I had this exact same problem last night. I wonder if it's been caused by one of the recent updates? I don't use Photoshop much, I do most of my editing in Lightroom.
I closed it and opened the image directly in PS instead of from LR and it was OK then.

Funnily enough, I also wanted to try something I'd seen on youtube - I wanted to have a play with the Orton effect that Thomas Heaton talked about in his latest video.