GTARPS

So, I've managed to import textures alone following the process listed below:

Testing Process:

1. Navigated to my world file ('minecraftworlds')

2. Deleted the .json files for known resource and behavior packs and old resource and behavior packs

3. Deleted all packs from Resource Packs in the world folder

4. Deleted all packs from Behavior Packs in the world folder

5. Downloaded a pack as a test 'Flow's HD 64*64

6. Replaced some block .png(s) in the Flow folder with custom selected textures

7. Applied the pack through Minecraft to the world

8. Reset my Realm

9. Replaced my Realm world with the Minecraft world I just edited.

Result - All textures transferred successfully.

Note: I have yet to try behavior packs, however I will continue my bug testing and see if I can successfully transfer a behavior pack to the realm.

Yes, quite experienced. I build systems frequently. 

https://youtu.be/fxwzQBzYOhc

No, there are several addons applied in addition to the separately made test resource pack.

I simply opened the editor, changed  the last opened version to 1.7.0.0, saved, then replaced the Realm world with the edited world and it did not resolve the issue. 

Shawn,

I'm afraid that didn't work, either. I truly wish we wouldn't have to resort to trial and error in an effort to fix bugs ourselves. It seems pretty clear that something is off with the way worlds are being transferred to realms, yet the issue still hasn't been identified. Perhaps it could be that the bug testing is taking place solely on servers not in my region (U.S. SouthEast). At any rate it's not fixed on my end.

Respectfully, I don't know who the bug testers were in this case, but this issue is most certainly not resolved. 

I utilized a very basic process to confirm this:

Step One: Located and downloaded 16*16 .png images from google (for custom block textures).

Step Two: Created addon folder and placed the .png(s) into addon_name>textures>blocks, renaming them after glass and cobblestone.

Step Three: Created a manifest.json file with the following code:

// code placeholder

{
  "format_version": 1,
  "header": {
    "description": "2019_Blocks_Textured",
    "name": "2019_Blocks_Textured",
    "uuid": "8411769e-c315-11e8-a343-529269fb1459",
    "version": [1, 0, 0],
    "min_engine_version": [1, 2, 6 ]
  },
  "modules": [
    {
      "description": "2019_Blocks_Textured",
      "type": "resources",
      "uuid": "c6b9723e-c398-11e8-a343-529269fb1459",
      "version": [1, 0, 0]      
    }
  ]
}

Step Four: Located and downloaded a suitable pack photo (pack_icon.png) and inserted it into the main addon folder.

Step Five: Opened Minecraft Windows 10 Edition, applied Resource Pack to vanilla world, opened the world and confirmed the custom textures were applied successfully. 

Step Six: Reset my Realm, then replaced the world with my world that had the new resource pack applied.

Step Seven: Opened the Realm to find the textures did not transfer.

Important Note: I attempted to download the world from my Realm on console, and the pack downloaded successfully, I was able to play the world (not on the realm) on my console after reapplying and reordering the pack.

I have tried this with all of my custom packs, and it seems that the files transfer, but somewhere when being transferred to the realm they disable themselves, despite downloading from the realm to console and W10E (albeit in random order).

I sincerely urge that this issue be remedied, as I can't see myself renewing my subscription if it is not. So many of my community members are depending on a fix, and many are growing frustrated seeing no signs of a resolution. These workarounds are not at all fullproof, and they seem to merely filter out a tiny portion of the issue rather than resolving it.

It seems 1.8 still hasn't solved this. I am beyond frustrated.