The first verse of chapter 1, canto 1 of Srimad Bhagavatam translated by Srila Prabhupada is the following
oṁ namo bhagavate vāsudevāya
janmādy asya yato 'nvayād itarataś cārtheṣv abhijñaḥ svarāṭ
tene brahma hṛdā ya ādi-kavaye muhyanti yat sūrayaḥ
tejo-vāri-mṛdāṁ yathā vinimayo yatra tri-sargo 'mṛṣā
dhāmnā svena sadā nirasta-kuhakaṁ satyaṁ paraṁ dhīmahi (TEXT 1)
The translation is as follows
O my Lord, Śrī Kṛṣṇa, son of Vasudeva, O all-pervading Personality of Godhead, I offer my respectful obeisances unto You. I meditate upon Lord Śrī Kṛṣṇa because He is the Absolute Truth and the primeval cause of all causes of the creation, sustenance and destruction of the manifested universes. He is directly and indirectly conscious of all manifestations, and He is independent because there is no other cause beyond Him. It is He only who first imparted the Vedic knowledge unto the heart of Brahmājī, the original living being. By Him even the great sages and demigods are placed into illusion, as one is bewildered by the illusory representations of water seen in fire, or land seen on water. Only because of Him do the material universes, temporarily manifested by the reactions of the three modes of nature, appear factual, although they are unreal. I therefore meditate upon Him, Lord Śrī Kṛṣṇa, who is eternally existent in the transcendental abode, which is forever free from the illusory representations of the material world. I meditate upon Him, for He is the Absolute Truth.
However, in the Srimad Bhagavatam translated by Swami Tapasyananda who largely follows Sridhara's interpretation, the first verse is as follows
जन्माद्यस्य यतोऽन्वयादितरतश्चार्थेष्वभिज्ञः स्वराट् तेने ब्रह्म हृदा य आदिकवये मुह्यन्ति यत्सूरयः ।
तेजोवारिमृदां यथा विनिमयो यत्र त्रिसर्गोऽमृषा धाम्ना स्वेन सदा निरस्तकुहकं सत्यं परं धीमहि ।। 1 ।।
He from whom the creation, sustenance and dissolution of the universe take place; who is both the material and instrumental cause of it; who is omniscient; who is the only One having self-mastery, being the one independent entity; who illumined the mind of Brahma with the Vedic revelation whose wisdom is the wonder of even the greatest of sages; in whom the worlds, the manifestation of the three Gunas, subsist in reality without in the least affecting Him, just as the combinations of material elements like fire, water, and earth subsist in their causes without changing their elemental nature; in whose light of consciousness there is no place for anything false—on that Truth Supreme we meditate. (translation)
The non-sectarian translation such as the translation by Bibek Debroy and the translation published by Motilal Banarsidass also more or less like Swami Tapasyananda's translation.
My question is whether "Om Namah Bhagavate Vasudevay" is part of the first verse or not. If it is part of the first verse, then why no other translation mentioned it? If it is not part of the first verse, then where from Srila Prabhupada got it? It is not a question of different interpretations. This Sanskrit phrase is altogether missing in some translations. Very strange. Any explanation?