Error occurred right after setting background color on a cWebTabpage to "ltgrey" in studio (18.1 web) and clicking in the previewer

C:\vdf18B1\Bin\Studio.exe
COM object method invocation error. Invalid CDS node handle
Error: 4399
Please report this error to Data Access Corporation
GET_COMGETPARENT (11835) - oCDS (2923) - at address 84201
GET_TREENODEMATCHINGCDSNODE (16320) - oTree (2946) - at address 198795
MSG_ONCHANGECURRENTNODE (12560) - oCodeExplorer (2922) - at address 198927
MSG_SETCURRENTNODES (12581) - oFileVDF (3730) - at address 89854
GET_EXECUTE@1 (11960) - oStudioCommand (764) - at address 135460
MSG_ONCOMMAND@2 (11977) - oActionManager (611) - at address 85283
MSG_ONCOMMANDSTRING (11978) - oActionManager (611) - at address 85301
MSG_ONIDLE (1564) - oMain (774) - at address 150555
[start] - at address 236275