Chart export image different from actual

Hi all,
I'm plotting RSI chart as per formula below:

_SECTION_BEGIN( "RSI" );
SetChartOptions( 1, 0, ChartGrid30 | ChartGrid70, 0, 0,0 );
periods = Param( "Periods", 14, 1, 200, 1 );
z = RSI( periods );

RSILineColor = ParamColor( "RSI Line Color", ColorRGB( 0, 153, 204 ) );
RSIOverboughtColor = ParamColor( "RSI Overbought Color", ColorRGB(235,77,92) );
RSIOversoldColor = ParamColor( "RSI Oversold Color", ColorRGB(83,185,135) );



oversold = Param( "Oversold level", 30, 1, 100, 1 );
overbought = Param( "Overbought level", 70, 1, 100, 1 );

Plot( z, _DEFAULT_NAME(), RSILineColor , styleLine | styleThick);
Plot( 50, _DEFAULT_NAME(), RSILineColor , styleNoLine | styleNoTitle | styleNoLabel);
Plot( overbought, _DEFAULT_NAME(), RSILineColor , styleNoLine| styleNoTitle | styleNoLabel);
Plot( oversold, _DEFAULT_NAME(), RSILineColor , styleNoLine | styleNoTitle | styleNoLabel);
PlotOHLC( z, z, 50, z, "", IIf( z > 50, RSIOverboughtColor, RSIOversoldColor ), styleCloud | styleClipMinMax | styleNoLabel, oversold, overbought );



PlotGrid( oversold, colorGrey40, 10,1,False );
PlotGrid ( 50, colorGrey40,False );
PlotGrid( overbought, colorGrey40, 10,1,False );

This the plot I'm seeing in Amibroker:
Broker_2019-12-19_21-27-37

However, when I export to PDF or go Edit > Image > Copy As Bitmap and paste to Paint, this is what I get:

image

Has anyone experience the same? Appreciate any advice as to why this is happening.

Thanks heaps.