In your Question, you have mentioned only 1st part of Bhagavad Gita 9.29. Here is the complete Shloka:
समोऽहं सर्वभूतेषु न मे द्वेष्योऽस्ति न प्रियः।
ये भजन्ति तु मां भक्त्या मयि ते तेषु चाप्यहम्।।9.29।।
And this is how Swami Gambirananda translates it:
I am impartial towards all beings; to Me there is none detastable or none dear. But those who worship Me with devotion, they exist in Me, and I too exist in them.
This would be more clear from English Translation Of Sri Shankaracharya's Sanskrit Commentary By Swami Gambirananda:
Aham, I; am samah, impartial, eal; sarva-bhutesu, towards all beings; me, to Me; na asti, there is none; dvesyah, detestable; na, none; priyah, dear.
I am like fire: As fire does not ward off cold from those who are afar, but removes it from those who apporach, near, similarly I favour the devotees, not others.
Tu, but; ye, those who approach near, similarly I favour the devotees, not others. Tu, but; ye, those who; bhajanti, worship Me, God; bhaktya, with devotion; te they; exist mayi, in Me-by their very nature; ['Their mind becomes fit for My manifestation, as it has been purified by following the virtuous path.'] they do not exist in Me because of My love, Ca, and; aham, I; api, too; naturally exist tesu, in them, not in others. Thus there is no hatred towards them (the latter). 'Listen to the greatness of devotion to Me:'
So there is no contradiction between 9.29 and 10.1 Shlokas.