Layer dimming not working. What am I doing wrong?

[#1]

Fifteen years ago, the first thing I learned when I first opened Illustrator was to layer lock and turn it into a template. What changed?

I have two layers with different objects in each. I double click my bottom layer and choose: Template + Dim images to 50%.

Layer locks, but opacity stays the same. I'm on the latest AI. What's going on?

[#2]

Fifteen years ago, the first thing I learned when I first opened Illustrator was to layer lock and turn it into a template. What changed?

I have two layers with different objects in each. I double click my bottom layer and choose: Template + Dim images to 50%.

Layer locks, but opacity stays the same. I'm on the latest AI. What's going on?

[#3]

Are the objects on the layer images? Because that's what that option dims, not regular drawing objects.

[#4]

It's a JPG.

[#5]

Please show a screenshot of the problem. Layers panel should be in it.

[#6]

I have the same problem but with a drawing not a JPEG did you figure it out yet?

[#7]

It won't work with a drawing. It only works with placed images.

[#8]

Try applying Effect >  Rasterize... to the vector drawing.

This will trick Illustrator in treating it as an image.

Because it is an Effect you can alway delete it or turn it off in the Appearance panel.