Recently-Updated Modpack Not Reinstalling Correctly

[Firefly1337]

I have recently updated my modpack, MaelstromMC, to version 1.3. This update included four mods: Flan's FutureCraft Content Pack, Journey Map, Not Enough Items, and Waila Harvestability. I uploaded the new version of the modpack to my file host and obtained the direct download link to copy into the modpack destination in the "Modpack Location" section of the "Settings". I made sure to click "Update Modpack".

However, despite all this, when I reinstalled the modpack using the Technic Launcher, the new mods did not download. I made sure I was choosing the "Latest Version" option. I also made sure the 1.3 version of the modpack was being downloaded, and it was; the ZIP file that was being downloaded was definitely the correct version. I loaded the mods in the standard Minecraft Forge client, and they loaded properly, so I know it's not a mod incompatibility issue. My friend was also having the same issue. When we both tried joining the server, the server gave the disheartening "Fatally missing blocks and items" message. Yes, I added the individual mods to the server as well.

The only thing that seems to "fix" this issue is a completely fresh install, as in, deleting the pack from one's system entirely and reinstalling; basically, a from-scratch install. However, I do not want my players to have to do this because it resets their controls, audio, and other custom settings.

If someone could instruct me on how to fix this problem and prevent it from happening again, I would be greatly appreciative.

[AetherPirate]

Did you increment the version number of the pack? Was it at 1.2 before?

[Firefly1337]

Yes, I made sure I incremented the pack. It was at 1.2.1 previously. The additional ".1" indicates a very slight change in the pack.