Riccardo, What is the actual provenance of this painting? Did the reference you read state Leuchtenberg then Alexander Palace relating to c1800s? Is there more information i.e. Leuchtenberg, Tsar AII possibly, Tsarskoe Selo, - to narrow down the search criteria. If it relates to Tsarskoe Selo, then it could possibly have been displayed in the Catherine Palace i.e. AI rooms, Zubov wing. I have searched the Yakolev descriptions and with a limited understanding of Russian have been only able to find the one painting by Albrecht that was still in the Alexander Palace after the revolution. If the painting was in the AP prior to 1917 but moved subsequently for whatever reason by NII, did it survive the evacuation in 1941 and now in Pavlovsk for example.
Joanna