Exodus 40:35

ולא יכל משה לבא אל אהל מועד AND MOSES WAS NOT ABLE TO COME INTO THE APPOINTED TENT — But another verse says, (Numbers 7:89) “And when Moses came into the appointed tent [to speak with Him then he heard the voice]”! There comes, however, a third verse and reconciles these apparently contradictory verses, for it says here כי שכן עליו הענן “For (or when) the cloud abode thereon (on the appointed tent)”. Hence you may say: so long as the cloud was upon it “he was not able to come into the appointed tent”, but as soon as the cloud disappeared he entered it and spoke with Him (Sifra, Braita d'Rabbi Yishmael 18).

וְלֹא־יָכֹ֣ל מֹשֶׁ֗ה לָבוֹא֙ אֶל־אֹ֣הֶל מוֹעֵ֔ד כִּֽי־שָׁכַ֥ן עָלָ֖יו הֶעָנָ֑ן וּכְב֣וֹד יְהֹוָ֔ה מָלֵ֖א אֶת־הַמִּשְׁכָּֽן׃

And Moshe was not able to enter the Tent of Meeting, because the cloud rested on it, and the glory of the Lord filled the tabernacle.