Downloads not playing

Hi folks.
I've just joined up because I have a very strange issue and I don't know what to do about it.
I've come here because I don't know where else to go or what else to do.
The issue is this: For a long time, I have been able to download TV shows (primarily in MP4 but now many in MKV) which have played flawlessly on our TV or through the USB slot on our Blu-ray player.
But earlier this year, for some reason nearly all the shows I got just wouldn't play in either machine.
I thought I had tracked the problem down to being a matter of video fps (our equipment only likes 20 to 30 fps), so I'd convert them using HandBrake and away we'd go.
Now, I check every download to see what its framerate is, and even if it's within those limits (it's normally 23.976 fps) ... nope, no go.
I even re-encoded some of them in HandBrake so the fps was within those limits, but still no luck!
What I want to ask is, does anyone know whether uploaders/encoders have changed the way they do things or how they're encoding these things so that they become more problematic?
Or has there been an announcement somewhere that I haven't seen or something?
It's really frustrating, because I thought I'd fathomed it out, only to be caught again.
Anyway, advice or thoughts would be welcome.
Regards,

scoopyx.

can you see any information in logs of the player if you run it through on the laptop - does it work ok on the laptop?

bluray machine probably updated to block non-certified .mkv and\or .mp4 this happened to my Sony Bluray player.

Hello again folks, and thank you for the responses.
I actually think I've been able to figure this out (!!!)
Our equipment appears to not like either the AC-3 audio codec (all the time) or the MKV container (some of the time).
Regarding the laptop, no, I hadn't actually done that - hadn't thought of it, actually.
But I guess it's now basically moot anyway, because if I run things through HandBrake with settings that I am certain will work on our equipment, everything seems to be happy.
I just make sure it's set to output to MP4, the audio codec is AAC and the FPS is within the limits of our equipment, and away we go.
I still don't know for certain what changed from before, but I'm not complaining.
My wife (and me, to a lesser degree) can now watch the shows we want to.
Thanks for everything folks, and I'll be back.
Regards,

scoopyx.

Good to hear you got it working.