Emulator

Game Name?

Okami

Game ID?

ROWP08

What's the problem? Describe what went wrong in few words.

If Anti-aliasing is enabled in the game settings, rejuvenation brush (painting over missing objects to make them appear) will not work.
When you start painting over such an object, game freezes for a very short while (0.5s maybe ?) and resumes, but the brush returns to normal painting mode - meaning you keep drawing lines as normal, instead of dropping ink blots on the object as it should.
Then, if you release B, nothing happens.

What did you expect to happen instead?

I expect the brush to enter "rejuvenation mode" and drop ink blots all over the shape of the object to rebuild. When you release B, the object should be recreated.

What steps will reproduce the problem?

0. Enable anti-alisaing in Dolphin settings
1. Start a new game. Skip through all cinematics with +
2. Enter the cave under the tree.
3. Move forward until you receive the rejuvenation power for the brush
4. Try painting over the missing celestial river

Which versions of Dolphin did you test on?

4.0-5962

Does using an older version of Dolphin solve your issue? If yes, which
versions of Dolphin used to work?

No

What are your PC specifications? (including, but not limited to: Operating
System, CPU and GPU)

Alienware M14X
Windows 7
Core i7-2670QM
Nvidia GT 555M

Is there any other relevant information? (e.g. logs, screenshots,
configuration files)

The compatibility page at https://wiki.dolphin-emu.org/index.php?title=Ōkami mentions that rejuvenation brush freezes the screen for a few seconds but then works normally.
This is true... as long as anti-alisaing is disabled.

If anti-aliasing is enabled, however, the freeze time will be much shorter but the rejuvenation brush won't lock, as exmplained above.