Yep. +to it.
Especially Special Delivery xD
But.Srsly:
Sometimes also "collection" show some challenge completed 100%(or one collection fully 100%),but one day later(or after playing a bit) it may be different %.

Same Problem here.

Want to get the Achievement

"Buster Cannon: Deal 5,000,000 damage with Cannonball Towers."

I got ingame the Achievement Buster Cannon 3: Deal 50.000.000 Damage, but not the steam achievement for 5.000.000 Damage

Btw. I should have all 4 damage achievements on steam, but i got none of them

I took some pictures on my steam profile https://steamcommunity.com/profiles/76561198048413740/ So that should show which achievements I should have. 

Yes,

Unlocked multiple challenges in-game, for example the use 100 environmental traps and deal 5000000 damage with cannons, but they did not unlock as steam achievement (maybe achievement trigger bugged?)

Aside from that, level achievements did still unlock for me on steam.

Also having problems with in-game tracking.  No idea where I am with spooky challenges because my progress changes every time I look.

Somehow I have gotten 100% for Special Delivery, while Special Deliver 1 + 2 are at 0%.

Earlier today, all these were 100% except for the Special Delivery 3 and the only reason I check is because Steam told me it is the last achievement for me to complete.

same for me,

especially the new achievments after june 20th, 2017

e.g. "The Defender" and "Heroes United" leveled 6 heroes today to level 50, no achievments T.T

greets vorgash

Got the same problem with "The Zapper" already had the ingame Achievment, but even after getting again 5.000.000 dmg with Lightning Aura there was no change :/