p4 plugin 1.11.0
The Perforce plugin's ConsoleAnnotator relies on finding matching "(p4):cmd:" and "(p4):stop:" strings in the log in order to collapse Perforce commands in the log. We're seeing the "(p4):stop:" log for a 'p4 sync' call appear only after the Jenkinsfile has already moved on to running other commands. This causes the p4 plugin to collapse logs from other processes, making the console log seem as if it is missing output at first.
Here's a portion of the logs for a project that is checked out from Perforce, you can see that the 'p4 sync' command's :stop: log does not appear:
The last (p4):stop: eventually appears in the middle of other commands and console logs from there on out appear normally.