Beatmaps that you seem to CANNOT full combo no matter what

No matter how skilled or how long have we been playing LLSIF, there will always be "that one" (or two, or more) maps that you cannot seem to full combo despite your best efforts and your skill at its peak. Which beatmaps are these for you?

I'll start - I termed these beatmaps as my "Nemeses". I don't run Perfect Lockers, so all of these statements were made as if there's none on my team.

These are:

• HAPPY PARTY TRAIN EX - I actually find the EXR and MASTER beatmap easier than it. When it first appeared in-game, I already got it to A-clear (60+) yet never landed a full-combo. The MASTER map? Full-combo'd after just a few tries.
• Music S.T.A.R.T! MASTER - That single-side fast triplets will forever be the bane of my existence. There were times when I got past the triplet hell only for the Victory Rush to get the best of me.
• Brightest Melody MASTER - This is the only MASTER map in-game that I haven't got past B combo even once. That pre-chorus spray gets me 99.99% all the time. I even got a one-good play without any Perfect Locks once, and - predictably - it was in the middle of the song.