Hi there!
TLDR; Create a sample project for me replicating the error, and send the link to my discord: hakuenstudio. I will see what I can do.
Now, below I will list some reasons why this could be happening but also will share with you some thoughs. Please don't take the wrong way, I'm just trying to clarify things, I'm not mad at all.
1 - Your afirmative is wrong:
"Just started updating A LOT of older plugins, and this one seems to have completely broken something:"
- You can't know for sure that is MY plugin that broke something. When there is a plugin conflict, the right afirmative would be: "These two plugins are conflictiing with each other". You can't say that the problem lies on one or another.
You updated my plugin version, but also Visustella plugin version changed. The two plugins changed, the way the codes communicate with each other will change. Even if only one plugin changes, that does not mean he is the one that broke something. Sometimes, fixing a bug, adding a new feature, will make changes into the code, and there will be no way for two plugins to work together after these changes. Sometimes, we can adjust things and make it work together, but sometimes not.
2 - Obfuscated code
- Visustella plugins are obfuscated. This means encrypted. I cannot see what they are doing. Therefore, I can't compare both codes and see what is conflicting between them. What I can try to do, is a process of trial and error, that takes much more time and it is harder, than if I could just take a look at their codes to see where the problem lies.
I also cannot remove the obfuscation of their code, since it is against their terms of use.
3 - Visustella Terms of Use 6
If in case I manage to find the problem, I will need to follow this. I will have to ask them, wait for approval, and if they approve the compatibility patch that I MADE, that I took my time to search through my code and their obfuscated code, I will have to put that on THEIR WEBSITE, for free(that last is fine haha). Even if you pay me to do, I cannot do that.
On other words, I can only do a patch for this problem, if I manage to fix it by just using my plugin.
4 - Compatibility issue
I never see Visustella making compatibility patch for anyone, for any other plugin maker. The code obfuscation and their terms of use, also is a big setback to any other plugin maker that has the will to make a compatibility patch that involve their plugins.
I usually get requests like yours, and people always says that problem is on my side. But after the explanation above, it will not be easier to ask THEM to make a compatibility patch with my plugin? Because they could have access to both codes, since only they can see their code without obfuscation. I give my plugin for free for them to take a look.
What I mean with this is, they have all these setbacks to make compatibility with other plugin makers, and people don't see to take that into consideration when using their plugins. You need to know that, by using their plugins, this could be a reality on your project: They will not create compatibility patches with other plugin makers. And also equally true, other plugin makers(like me) will be higher desmotivated to create patches by have to follow their terms of use and take a look at a obfuscated code.
- So, my code is not obfuscated, but their code is obfuscated.
- I cannot see their code without obfuscation, but they can.
- As so, their are the ones who people should ask first to make a compatibility.
5 - Plugins with the same feature
Now, Visustella Message Core, on my opinion is a bloated feature plugin (as many others). What I mean is, it messes with way more things than just the Message System of RPG Maker. This make everything harder for compatibility. It also messes with choices and who knows more.
So, these two plugins are making changes on the RPG Maker choice system. It's high unlikely that they will work together. I know you said that on a previous version they worked just fine. But that is luck, an exception. Usually plugins that does the same thing does not work together. It's like having two plugins that changes the Status Window Menu. Or they will not work together, or they will work with some problems.
6 - Use the previous version
Have saying that all, if I didn't manage to fix the problem, you may consider using the previous version of my plugin. Or stop using one of them. Or ask them to try make a compatibility, I could my plugin to them with no problems.