In 1.12.2 and previously it was possible to use the execute command to run plugin commands as a specific player (with /execute @p ~ ~ ~ <plugincommand>), this is no longer possible with 1.13(.1? Not sure if it was an issue previously too).

Tested with the new command format /execute as @p run test outputs [12:39:11] ...as @p run test<–[HERE] in the command block. (test is a command of a test plugin that I made, same issue happens with any other command)