I believe this may be a bug and have reproduced the error on my end. While I am currently not at the office, I have emailed myself a full list of reproduction steps to create a bug report once I am able to get back to the office. Until such time, I will leave this post unresolved. I have moved this post to the bug reports section as well.
Here’s some workaround info is someone stumbles into the same issue:
I use the “Print String” Node. I never mentioned before, that it’s expandable and has a “Print to Log” toggle.
I entered a bug report, UE-25907, to be assessed by the development staff. However I believe we are talking about two separate situations. The bug I have entered was specifically for the Log Text, Log Location, and Log Box Shape nodes not printing to the Blueprint Visual Debugger or to the output log, the method you have described above for print string is not a workaround but the intended functionality. You can choose to have the string printed to the log for an easier readout.