I am using 4.3 version and cannot package balnk projects (code-based project is OK).Do you guys haves this problem?
Build, then choose ‘save all’. If you don’t that will happen. So I am guessing this is what happened to you as well.
Here is hoping it will work 
/Mike
HI,I did as you said ,but it didnt work.Here I post my steps and errors of ouputlog.HelP!4.3 cannot package balnk projects - C++ - Epic Developer Community Forums
Hello,
Thank you for your report. We were not able to investigate this on the engine version you reported, but there have been many version changes to UE4 since this question was first posted. With a new version of the Engine comes new fixes and it is possible that this issue has changed or may no longer occur. Due to timetable of when this issue was first posted, we are marking this post as resolved for tracking purposes. If you are still experiencing the issue you reported in the current engine version, then please respond to this message with additional information and we will investigate as soon as possible. If you are experiencing a similar, but different issue at this time, could you please submit a new report for it.
Thank you.