My ESP build is unable to find include files from libraries.
I can build the same code in Arduino IDE just fine, whether it is for ESP or Arduino Uno.
But in VS+VM if I set the board to Arduino Uno it builds fine.
If I set it to any ESP variant the build fails at library header include. This is example test.ino contains just #include <LiquidCrystal_I2C.h> with empty setup() and loop().

Compiling 'Test' for 'WeMos D1(Retired)'
 
Test.ino: 2:31: fatal error: LiquidCrystal_I2C.h: No such file or directory
   #include <LiquidCrystal_I2C.h>
   compilation terminated

     An error was encountered during the 'Deep Search' library discovery process.
Build failed for project 'Test'


I have Arduino 1.8.5 installed.
Visual Studio 2015 community.
That library (if it matters) is the dfrobot I2CLCD lib here:-
https://github.com/marcoschwartz/LiquidCrystal_I2C

My sketchbook location in arduino is set to  "D:\SVN\Code\Arduino"
I have directories "libraries" and "Sketches" below this location. Everything builds just fine in Arduino IDE.
I have tried setting the same sketchbook location in vMicro but it does not help.
A similar setup but without a modified sketchbook location in Arduino setup works fine so it looks like it is something to do with this.
I tried duplicating all the library directories at the usual place (ie...documents/Arduino) but that did not help.
Rescan toolchain and libraries does not help.
Doing a rescan in Visual Micro Explorer does not help either.

Any suggestions?

Ah-ha!
It looks like it is the achitectures line and a difference in how it is parsed by vMicro vs the Arduino IDE.

It seems that vMicro only accepts the library if the architectures match. This library has architecture marked as AVR so vMicro does not make it avilable in ESP builds.
But it looks like Arduino IDE still makes the library available to architectures that don't match, but offers a warning instead.

If I change that line from "architectures=AVR" to "architectures=*" then it builds OK (and yes, it runs OK too).

I wonder, perhaps vMicro's behaviour should be changed to be the same as Arduino IDE?  The Arduino docs say:-

"In 1.5.x+, libraries placed in the user’s sketchbook folder (in the libraries/ subfolder) will be made available for all boards"

From: https://github.com/arduino/Arduino/wiki/Arduino-IDE-1.5:-Library-specification

In the next release of visual micro the architectures specified in each library.properties file is ignored because they are often wrong.

Both intellisense and build will allow any library for any architecture.

Thanks for the report.