Appreciate the responses.
I've successfully published everything but finding the root cause was not something I achieved. I have a hunch however, that it is because of the volume of changes I had between my local oml and the published version.
What I did to publish everything was open 3 instances of service studio.
The first instance shows the changes between the published and my local oml. I used this as my reference.
The second instance I had was used to publish things incrementally.
And the last instance I had was just to open the local oml.
I then, one by one, copied small increments of my changes (based on my reference) from the instance that has the local copy open to the one that publishes. Sometimes I could upload as much as 3~4 changes, but it also came to a time that I could only upload one at a time. It was excruciating.
Possible culprits of "huge changes" were, big logic components, variables that are large structures that hold more than 5 entities/structures inside.
I am glad that things have been "resolved" (probably forgot to copy some things but better than starting from scratch again.)
This experience has been very frustrating and highkey traumatizing. This is my first year using the platform and I can't believe it can't handle a huge amount of changes.