Andrey Vlasov was well regarded as a commander and given an elite command. His ‘Shock’ army (an army equipped for assault) drove into German lines during a counteroffensive at Leningrad, but his requests for reinforcement or to be allowed to withdraw were refused. The ‘front line’ in Russia was often very much a theory, with vast areas lightly manned. This allowed Vlasov to get into a threatening position but there is no doubt he felt betrayed by Stalin.
This is of course in the context of the Soviet officer corps in 1942: the purges had just killed most senior commanders, and competent military leadership was in high demand. Vlasov could rightly feel slighted, and he eventually surrendered.
It took some time for Vlasov to become a collaborator. The Germans used many foreign ‘legions’ in the war against the USSR and Vlasov was obviously anti communist enough, and had enough faith in eventual German victory (which appeared very likely at least until January 1943) to guardedly accept command of a unit drawn from Red Army prisoners. This was kept without weapons as a sort of propaganda unit for a long time and Vlasov’s support was guarded as he demanded it become a real force.
The Germans eventually made Valsov’s unit into something effective but only in 1944 when they were desperate for men and were using many non-Germans, especially in occupation duty and to supress rebellions.
Vlasov’s troops were sent in the control Slovakia but the rebellion there, very late in the war, seemed quite capable of overwhelming the Nazi occupation. No doubt Vlasov and his commanders could see the hopelessness of their situation, possibly they had a genuine affinity with the Slovak insurgents. Also quite possibly having survived Stalin and German captivity (few Russians did), they were in no mood to be killed fighting the Slovaks and again ‘got with the winning team’.
(The monarchists in Russia are such an anachronism they in all likelihood have to latch on to anyone they can who looks even a bit sympathetic to their cause!)