Unofficial Fallout 4 Patch

I did some testing and I think I found the problem. Cloak bonus is like "sneak_multiplier+0.2*corrected_sneak_multiplier", where sneak_multiplier is base_multiplier+sandman+ninja and corrected_sneak_multiplier should be = sneak_multiplier. But if Sandman is taken right before Cloak, the corrected_sneak_multiplier doesn't take account of Sandman bonus and it's base_multiplier+ninja instead of base_multiplier+sandman+ninja as it should be.

Bug #19677 suggested changing Cloak & Dagger to add value instead of multiplying, but the latest version of UFO4P makes no changes to that perk. The file url in one of the comments no longer works, so I can't confirm whether that's really how it was fixed, but if it was, it looks like it was reverted or something, possibly unintentionally.

Actually, it might help to determine what the "correct" multiplier with all three perks is. I can think of about 4 options so far:
1. If Cloak and Dagger is changed to add to the sneak attack multiplier instead of multiplying, and the 20% for C&D is relative to the base sneak attack bonus, that produces an ending multiplier of 4.4x
2. As above, but with C&D adjusted by conditions to be relative to the Ninja sneak attack bonus, the final multiplier is 4.7x
3. As #2, but also boost Mister Sandman to match description (adding 0.5 to the default 2.0 multiplier without the other perks is 2.5x, a 25% increase, rather than the claimed 50%), 5.2x
4. Let the bonuses stack multiplicatively for all three perks: Ninja states that rank 3 gives 3.5x normal damage for ranged weapons, which can be done by multiplying the default 2.0 by 1.75. 2.0 * 1.75 * 1.5 * 1.2 = 6.3x

Sorry for multiple comments, but I did some testing and experimenting, and it looks like the UFO4P "fix" for #19677 was to bump the "priority" of the entry points in the Ninja perks to 1 instead of 0, but Cloak and Dagger still has the same priority as Mister Sandman, still leading to inconsistent results depending on the order the perks are taken.

I tried making a mini-mod that changed the priorities, and with Cloak and Dagger at priority 10 (though 2 would probably work just as well), the multiplier was 4.4x, but consistent across all ten sequences of perk-taking I tested (which included some where sandman and ninja were partially leveled when adding cloak, then maxed after).

Changing Sandman's priority to 2 produced a consistent multiplier of 4.8x, and even worked for a game where I'd already taken the perks and ended up with a 4.4x multiplier (partly because I had a conflicting perk-changing mod that cancelled out UFO4P's changes to the Ninja perk)