Note2: If I set the effects to 72dpi in Document Raster settings, then I get a drastically reduced file - but then that shows that illustrator is not saving this information as vector (what could be simpler than remembering the colour, the offset and size of blur) but somehow rendering these dropshadows as images.
I've included my save settings that I've used since the beginning. I've been using illustrator since 1989 so I'm pretty au fai with the software and its bugs. But the fact that this happens in the last four iterations of illustrator along with the broken shadows is pretty annoying. I do wish bugs were given as much attention as whatever new generative AI bloat we get added to justify the subscription. But here we are.
Thanks for the response.

Hi Egor, the artboard is 700x500mm - though the same thing happens with an artboard much smaller.
I'm not using 'Create PDF Compatible file' at all - I never use that. So the drop-shadow information is effectively a vector in that file. It's obviously a bug as even if I dropped in the dropshadows as image files - I wouldn't get a 450MB uncompressed illustrator file.. Or wait over 30 seconds for it to save.
And my 300dpi exported PDF is less than 15MB, so rasters never need to get as big as 450MB.
Basically I have a relatively simple file with 4 dropshadows in it and each instance is adding around 400MB to the file, making it over 2GB, even if I rasterized the entire file at 300dpi and saved it as an uncompressed TIFF is wouldn't as large as my illustrator file with ONE dropshadow (uncompressed).
Now… compressing it helps, but it's still takes too long to save and is obviously compressing that 3GB down.

Still broken in 29.2.1

Not fixed in 29.0.1

Still not working in 2025 version 29.0. Coming up on 5 years since the original post.

Still not working in 28.5. That seems like a long time. Since 24.0.1 and probably before.

I'm having a similar problem using two outer glow effects on a big circle, see attachment. Version 28.5 on macOS.

I have the same issue.
28.3.

Still doing it in 28.3

Still not working in Illustrator 28.2

It used to be messed up in InDesign back in July 2021, but I tried it again and it seems to be fixed. I can save it as a PDF in InDesign and bring it into Illustrator, but that adds more steps and is kind of a pain. At least I have a workaround now.

Here is a JPEG of what I see and print in case the AI file doesn't give you the error.

Not working correctly in 27.8.1. Disabling GPU doesn't affect it.

Brad, Damian, does it help to disable GPU mode?
If it does — can you please provide the exact full spec of your machine?
OS build, GPU model, driver version?
Please also provide the actual test file in the .ai format, so the team can try to replicate the issue on their side and see what is wrong?

Still not fixed... 27.8.1

Why are we paying a monthly subscription if your BASIC effects don't even operate correctly?

3 years and counting...

Not Fixed 27.0.1

Had hopes this would be fixed in 27.0 but it's not

Still broken as of 10/7/22 after update to 26.5

Still in 26.5.

Not fixed in 26.4.1