Importing from .pst misses Sent Items emails

Hi - I’m importing a pst with several folders, including Inbox, Sent Items and a couple of others. Import in eMClient finishes successfully, and the messages in all folders look fine except for Sent Items - I have about 500 messages there and only one (!) shows after importing (a random one - not the chronological first or last). I’m importing the whole .pst into a separate local folder as the root for the imported hierarchy.
Reimporting the same .pst back into Outlook for testing, shows the messages correctly.
Is there anything I’m missing?

Thanks a bunch!