I started as a tribal Ibadi in the Sahara, conveted to Iqta, conquered a sufficiently large realm down there, then made a new Empire by decision and implemented Imperial Administration law, changing my government form to the new muslim Imperial: al-Mulk. However, when I give out higher titles to Iqta vassals, they briefly become al-Mulk but almost instantly revert to Iqta. I gave a freshly revoked duchy to an Iqta count. I gave a pre-existing (used it in the Empire creation) kingdom to an Iqta duke. I gave a freshly revoked duchy and a freshly created kingdom to an iqta count. All three became al-Mulk then reverted to Iqta. What's going on?