According to those inside Syrian goverment and Bashar's inner circle, he refuses all dealings with Turkey and especially Erdoğan for no other reason than the fact he is upset with Erdoğan. If u knew they use to be good friends, hell their families use to go on vacation together to turkish beachside resorts and they enjoyed many private dinners together and amicable state visits. However after Erdoğan ended up going all in with the rebels and terrorists Bashar was reportedly highly upset and felt betrayed on a personal level. Imagine the only reason HTS aka Rebranded Al Nusra Front successfully takes over Syria is because Bashar couldn't pull up his big boy pants and put his feelings aside to negotiate.At that time, Erdogan was trying to convince Bashar to resolve the issues between them.