Two years ago sketch compiled successfully. 
Now, with old and new Blynk libraries I got errors.
Arduino IDE compiles OK.

If in your sketch, do you have a layout similar to below:

//************************** Includes  ****************************
#include "FlashIR.h"
#include "CheckForUpdates.h"
//**************************  Blynk Includes  ****************************
//#define BLYNK_PRINT Serial    // Comment this out to disable prints and save space
//**************************  OTA Initialization  ****************************
int FW_VERSION = 3005; //OTA version with classes on local server

#include <ESP8266WiFi.h>
#define BLYNK_TIMEOUT_MS  750  // must be BEFORE BlynkSimpleEsp8266.h doesn't work !!!
#define BLYNK_HEARTBEAT   17   // must be BEFORE BlynkSimpleEsp8266.h works OK as 17s
#include <BlynkSimpleEsp8266.h>
//**************************  Blynk Initialization  ****************************
 

Then adding a dummy function beneath the "#include <BlynkSimpleEsp8266.h>" ensures the prototypes are injected at the correct point in the sketch.

void putPrototypesHere(){} 

The change in result between the versions is due to how Visual Micro now generates the function prototypes and in this case it is adding them to the CPP too early, which the addition above avoids.