Just gave this a look now that it's Monday and I'm in the office. Saw this over the weekend and was a bit surprised to see a difference described, given the starting point for Liss R was just to copy/paste the Zhonya's logic. Figured something might have changed over time though.
What I found testing this out was:
- Both Liss R and Zhonya's will buffer movement commands regardless of when during the stasis effect they're entered.
- Neither seems to buffer Flash at all, if you're able to do so with Zhonya's let me know how, I'm not seeing it.
- Liss R will let you buffer Q and W, but only if you cast it right before the R wears off. E can't be buffered
- Zhonya's will let you buffer Q, W and E, provided you cast them at least (roughly) halfway through the Zhonya's duration.
- Liss R will let you buffer Zhonya's, with a pretty generous cast window (second half of the duration again?)
- Zhonya's will not let you buffer Liss R at all on Liss herself (didn't test on enemy cast)
Now, that's the result of 10 minutes testing things out, so won't necessarily be fully comprehensive. If you're seeing different results in practice tool, would love to hear about it (I'm just using an internal environment with no CDs for this, which should be the same, but is very occasionally different).
In terms of possible steps forward here, when time permits I'll do some poking around, see if I can identify what's causing the inconsistencies here. Might be possible to get some of the buffering cases that aren't working in both cases at present to work and ship those changes with the other upcoming Lissandra stuff. Can't make any specific promises though at present.
ETA on the changes is sometime this year. Main issue recently was that the visual effects for the passive were reading as too similar to the ult, leading to confusion over whether her R was on CD or not. That seems mainly fixed with recent iterations, so next step will be looking at skin effects.
Only slightly related, but since I'm talking about Lissandra anyway, will also have some slight tweaks to her AAs in that package as well. Speeding them up slightly and making the animation better synced with when you'd expect it to launch the missile, which should also make things feel better even if it doesn't technically change gameplay (makes it easier to read/feel more natural).
's ultimate. When cast it on yourself, it acts as 
's active : she becomes invulnerable and untargetable for 2.5s, but is unable to take any action. Yet, there is something different from how 
