Including module header breaks FontCache.h

Hi! I’ve followed this tutorial about linking static libraries

But whenever I try to add a custom header file on a test actor, with the function declarations, this happens:

2>C:\Program Files (x86)\Epic Games\4.11\Engine\Source\Runtime\SlateCore\Public\Fonts\FontCache.h(232): error C2059: syntax error: 'constant'
2>C:\Program Files (x86)\Epic Games\4.11\Engine\Source\Runtime\SlateCore\Public\Fonts\FontCache.h(232): error C2238: unexpected token(s) preceding ';'
2>C:\Program Files (x86)\Epic Games\4.11\Engine\Source\Runtime\SlateCore\Public\Fonts\FontCache.h(227): error C2059: syntax error: 'constant'
2>C:\Program Files (x86)\Epic Games\4.11\Engine\Source\Runtime\SlateCore\Public\Fonts\FontCache.h(397): error C2059: syntax error: 'constant'
2>C:\Program Files (x86)\Epic Games\4.11\Engine\Source\Runtime\SlateCore\Public\Fonts\FontCache.h(401): error C2039: 'InSourceTextIndex': is not a member of 'FShapedGlyphSequence::FSourceTextRange'
2>  C:\Program Files (x86)\Epic Games\4.11\Engine\Source\Runtime\SlateCore\Public\Fonts\FontCache.h(224): note: see declaration of 'FShapedGlyphSequence::FSourceTextRange'
2>C:\Program Files (x86)\Epic Games\4.11\Engine\Source\Runtime\SlateCore\Public\Fonts\FontCache.h(402): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
2>C:\Program Files (x86)\Epic Games\4.11\Engine\Source\Runtime\SlateCore\Public\Fonts\FontCache.h(402): error C2039: 'int32': is not a member of 'FShapedGlyphSequence::FSourceTextRange'
2>  C:\Program Files (x86)\Epic Games\4.11\Engine\Source\Runtime\SlateCore\Public\Fonts\FontCache.h(224): note: see declaration of 'FShapedGlyphSequence::FSourceTextRange'
2>C:\Program Files (x86)\Epic Games\4.11\Engine\Source\Runtime\SlateCore\Public\Fonts\FontCache.h(402): error C2146: syntax error: missing ';' before identifier 'InternalIndex'
2>C:\Program Files (x86)\Epic Games\4.11\Engine\Source\Runtime\SlateCore\Public\Fonts\FontCache.h(402): error C2039: 'InternalIndex': is not a member of 'FShapedGlyphSequence::FSourceTextRange'
2>  C:\Program Files (x86)\Epic Games\4.11\Engine\Source\Runtime\SlateCore\Public\Fonts\FontCache.h(224): note: see declaration of 'FShapedGlyphSequence::FSourceTextRange'
2>C:\Program Files (x86)\Epic Games\4.11\Engine\Source\Runtime\SlateCore\Public\Fonts\FontCache.h(402): error C2039: 'InSourceTextIndex': is not a member of 'FShapedGlyphSequence::FSourceTextRange'
2>  C:\Program Files (x86)\Epic Games\4.11\Engine\Source\Runtime\SlateCore\Public\Fonts\FontCache.h(224): note: see declaration of 'FShapedGlyphSequence::FSourceTextRange'
2>C:\Program Files (x86)\Epic Games\4.11\Engine\Source\Runtime\SlateCore\Public\Fonts\FontCache.h(402): error C2039: 'SourceTextRange': is not a member of 'FShapedGlyphSequence::FSourceTextRange'
2>  C:\Program Files (x86)\Epic Games\4.11\Engine\Source\Runtime\SlateCore\Public\Fonts\FontCache.h(224): note: see declaration of 'FShapedGlyphSequence::FSourceTextRange'
2>C:\Program Files (x86)\Epic Games\4.11\Engine\Source\Runtime\SlateCore\Public\Fonts\FontCache.h(403): error C2065: 'InternalIndex': undeclared identifier
2>  -------- End Detailed Actions Stats -----------------------------------------------------------

ServerActor.h

#pragma once

#include "GameFramework/Actor.h"
#include "snap7.h"
#include "ServerActor.generated.h"

UCLASS()
class TESTPLC_API AServerActor : public AActor
{
	GENERATED_BODY()

public:	
    
	// Sets default values for this actor's properties
	AServerActor();

	// Called when the game starts or when spawned
	virtual void BeginPlay() override;
	
	// Called every frame
	virtual void Tick( float DeltaSeconds ) override;  	
	
};

The header file is located in ThirdParty/Snap7/Includes and this route is included in the VC++ directories

Any help is greatly appreciated