Just as a point of reference, I purchased my new Digitakt only a month ago, and I do not seem to have this issue.
I can mute/unmute any and all tracks simultaneously, even doing an 8-fingered mute/unmute and it consistently mutes/unmutes the intended tracks.
I am on OS 1.11
Have those reporting problems tried creating a new project and seeing if it still happens? Sometimes old projects can get weird.
Also make sure all sync is off, you aren’t using overbridge, nothing is connected via USB/MIDI, funny stuff happens when a lot is going on.
It happens on a fresh new project with no devices connected and with no sequence data.
I also encountered this problem, with older OS versions too. Bought mine in June 2017.
I also have this issue… Happens nearly every time I try to unmute/mute more than 3 tracks at once.
I don’t have this problem, can mute/unmute any number of track without problem.
I have the same problem on my OT MK2.
Same 
That’s definitely not true, because other operations with multiple trigs works perfectly.
Which ones? Adding and removing multiple trigs at once also has issues for me
Definitely not the case because:
Yeah either way if there is a limitation 1) it should be reliable, 2) it should be specified by Elektron in the user manual.
I’m having this issue as well. When pressing many buttons at the same time in mute mode, some tracks are not affected. My workaround for this is to “roll” my mutes so that not all buttons are pressed at the same time. I haven’t tested this yet, but I think the mutes are less reliable while the Digitakt is playing than when it is stopped.
I wanted to bump this thread up. Haven’t heard back from Elektron again yet. I looked at a few YouTube performances on the Digitakt, seeing people mute/unmute multiple tracks with no issues, and I am really becoming anxious about this. I am not sure if this is a software issue or there is a batch of early Digitakts (sold in the first 12-18 months after sales started) that have some kind of hardware issue.
I’ve just spotted this on my A4 Mkii and I shall be seeking advice about whether it is a code/hardware issue or restricted to a batch of devices. As it stands it is unreliable/unworkable and therefore essentially buggy
You would have to develop a new muscle memory to quickly drumroll (e.g. 4 trigs) with a few ms between each activation, but when you do it intuitively simultaneously the success rate for four toggling properly is <50%, if you press 8 then the A4 will react slowly, it will flash all pressed trigs and yet still only toggle some, frequently less than half the trigs will be as expected. Again, no transport active
Works fine on AR MKii as it does on the older Analog boxes - it’d be good to know if it can be addressed with a firmware update, I had no idea this was a known issue for the DT, it sounds very similar
Okay, good, so now we have confirmed that this issue is not limited to DT but also happens on OT mkII and A4 mkII. I think each one of us needs to report this to Elektron support so that they see this is not an isolated issue but a widespread one, and bump it up on their update todo list! This is annoying in studio but is actually a huge issue live.
Picked up my DT 3 months ago and I’m having this issue. Maybe it was from an old batch, I don’t know. I’ve learned to roll as well, but I wish I could just slam the buttons when I’m bringing all the drums in at once. I’m just glad it’s apparently not an hardware issue. Please fix this !
Happens on my DT less than 6 months old, noticed with sequencer running and 4+ mutes hit, but not necessarily limited to that. Never noticed a key not triggering, just mutes. Maybe that’s why the digitone only has 4 tracks 
Did some of you guys file support tickets? Has anyone heard anything from Elektron about this? It’s an issue that I got used to, but it’s super frustrating nonetheless. I really hope someone from the company can jump into this conversation and provide an update.
I have this problem too, if I unmute more than 3 track simultaneously it starts work bad