Year not saving on a few random MP4's

So I have been tagging all of my movie files with poster artwork, as well as the year they came out with the intention that not only will I be able to browse all the cool posters when looking for a movie, but also to be able to with 1 click reorder them all by year.

Its been mostly working wonderfully but for some reason there has been a few files that simply will not save the year. It saves everything else but the year remains blank. I also checked and none of these are marked as "read only". What may be possible, though I honestly can't remember after tagging so many, is that they may have originally been marked as read only and I had Mp3Tag change it for me, because there were a few like that.

I do know that once I started going and removing the "read only" manually once alerted by Mp3Tag, instead of having the program do it, I have not had this issue any further. But that could be a coincidence.

Right now I have around 7 or 8 movies that I simply cannot tag with "year". I enter the year, I hit save, it acts like it did, but it does not. It's totally empty.

Any way to fix these files? Help would be greatly appreciated

Bump?

i cannot look over your shoulder, so I cannot tell what may be the difference to other files that work fine.
Problems with MP4 files that refuse to be tagged often come from files with Nero tags.
So check if you have these tags in the files. If you have, then I think the only way to get them taggable is to reencode them without Nero tags.

Edit at 23:27: For someone who gets impatient after 3 hours without answer and bumps the topic it is amazing that you have the time of more than one hour without reaction to this answer.
Bumping the topic while it is still top of the list usually does not speed up any replies.

I appreciate the reply. Less appreciative of the overly aggressive, simpsons comic book guy-like lecture.

Look man, if you want to help great, if not don't. Not sure why you need to come off like I somehow ruined your day and need to be talked down to. Not exactly welcoming to a new member.

But whatever, thanks anyway.

Im not really sure how to check for Nero files or if this is something I can do in mp3tag, but I managed to fix it by simply editing the file outside of mp3tag and adding in the missing data that way

Yes, this is exactly the way it works in this forum: either you get a comment/reply or you don't. No need to "bump" a topic.
And if you are a new member: take this as a kind advice how to get the help because otherwise discussions would too easily move into a direction that does not deal with the actual problem.

In some parts of the world, currently there are the Christian Easter holidays and/or some people are not at home, but traveling in the world, therefore be patient.

In post #5 you told us that you have managed the problem simply by editing the file outside of Mp3tag.
Now it would be of value for the Mp3tag community, to tell us in detail, what you have done outside by which utility with the effect, that Mp3tag now accepts the wanted change in the MP4 file, to enter a value for the inner tagfield YEAR.

After the outside change, does Mp3tag now be able to do the change within the MP4 file, as you wanted to do this in the beginning?

DD.20160327.1201.CEST