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Did you add all dotween dlls in Assemblies tab first? You won't see the Types until you add Assemblies. 

I've noticed the issue as well both in the main 2019.1.9 production project and my own fresh 2019.2.9 project that has only a bunch of store assets in it. 

It does not, however, reset after every restart.But the issue seems to be related with the startup of the project. 

Almost all Bolt units are generated via reflection and visualize what Unity already has. So Unity's Scripting API documentation is basically a list of units:

For units unique to Bolt you have to visit the manual as you mentioned:

There are too many units to learn them all and understand how they interact so the best approach is to look for tutorials that do something similar to what you want to achieve. Learn Hub covers most of the basics, it's the best place to start learning Bolt: My recommendation would be to start with the platformer tutorial - it touches upon most common topics of development in Unity from a character controller to loading scenes, enemy AI, etc. 

There's a script in AC's Community Wiki that links variables of both So when you change a variable in one asset, it also changes in the other. I don't know if it's up to date though, you'd have to test that yourself. 

Beyond that Bolt  can automatically generate nodes to access any commands in AC's API:

However, AC has its own visual scripting system that is not directly compatible with Bolt but can be controlled via the scripting API linked above. Assuming the Community variable sync works you could develop some systems in Bolt and others in AC.

It's hard to tell without seeing the graph. Are you sure you're not using rigidbody which is physics based?

Also, does this issue persists in a build or is it an editor only thing?

EDIT: I also highly recommend upgrading your Bolt and Unity versions. There have been many fixes and optimizations since 1.4.1.

Perhaps an alternative would be to change the header color of the unit according to type? That could consistently apply to all generic units.

Start with Bolt 1. It's stable and all tutorials are made for it. The current Bolt 2 alpha is meant only for testing purposes and in addition to lots of bugs it still lacks core Bolt 2 features. Right now Bolt 1 and Bolt 2 alpha 5 are very close in functionality so you won't lose anything by starting with Bolt 1.

And you'll be able to migrate your project to Bolt 2 when it's stable since it reads Bolt 1's graphs. 

In short, Bolt 2 is full of bugs and lacks major features coming in the next and last alpha. And even when that releases, it'll take months for it to get stable enough for actual production.

Bolt 2 is in active development, you can follow the progress for alpha 6 here:

Updates are posted on the Discord's #bolt-2 channel regularly.

You can disable automatic scene var object creation in Edit/Preferences/Bolt