[MM3-users] Importing config and archives only partially succeeded?

Today I have migrated about 30 mailinglists from mailman 2.1 to mailman 3.3.2 & Hyperkitty 1.3.3. Although no error responses were given when importing the 2.1 pck files, and neither for importing the archives, for about half of the mailinglists the hyperkitty webpage doesn't show any subscribers, nor archived emails. The imported members and other settings are correctly shown in the postorius page. Is there anything that I can verify why the archive is not shown on the hyperkitty page?The hyperkitty_email database table does contain the emails. Thanks in advance,Eric