vs2017 will not build, ctraders compiler works

possible vs2017 integration error
this is like how it happend.

cTrader Beta
made indicator xxx
made robot Bot1 with indicator xxx
Bot1 opening in vs2017 & build OK

made indicator yyy
consume yyy in Bot1
ot1 build in cTrader editor -> OK, Bot1 opening in vs2017 & build -> fails:
  Error    CS0246    The type or namespace name 'yyy' could not be found (are you missing a using directive or an assembly reference?)     

close & reopen cTrader
Bot1 build in cTrader editor => OK, Bot1 opening in vs2017 & build -> fails
close & reopen vs2017
​​​​​​​Bot1 build in cTrader editor => OK, Bot1 opening in vs2017 & build -> fails
- - -
creating new bot Bot2
pasting code Bot1 in Bot2
setting references to xxx and yyy

Bot2 build in cTrader editor -> OK,Bot2 opening in vs2017 & build -> OK

So it works in a clean start but not always when an indicator is added afterwards.