The process was flawed from the outset because the U.K. & France ("the West") didn't insist upon Czech or Soviet participation. That made it seem dismissive & arrogant to the Czechs & others. Then, a deal was agreed to that had a hole in it large enough to float an aircraft carrier through: It was only valid so long as Czechoslovakia remained a sovereign country.
When the deal was signed, Poland helped itself to a small part of the same Sudetenland that the "West" let Germany annex. It said that it was doing so to protect the people from the Germans. Worse still, it took three parts of Slovakia. The West neither said or did a thing about these annexations, which made the agreement hypocritical. That fact was clear to Czechoslovakia, but also to the U.S.S.R. & Poland. Mostly, it was so regarded by Mussolini, who quickly agreed to join Italy a full military alliance with Germany as a result.
The land seizure by Poland enraged the Slovaks. It was easy for Germany to encourage Slovakia to separate from the Czechs & declare as a sovereign country. Slovakia did so on 14 Mar. '39. As the Munich Agreement was then made invalid, Germany quickly annexed the Czech provinces. It used the reverse of the same argument Poland had used earlier: It did so to protect the Czechs from the Poles. They were then called the "Protectorate of Bohemia & Moravia."
On 23 Mar., Hungary began a short war with Slovakia to seize some of its territory. The "West" remained silent as this went on, intensifying the feeling in central Europe & the U.S.S.R. that the "West" was hypocritical.
On 1 Sep. '39, Slovakia contributed 3 infantry divisions to the German force that overran Poland. While the "West" quickly declared war on Germany, it didn't on Slovakia. It never did subsequently. It also never declared on the U.S.S.R. when it moved into its "sphere of influence" in Poland (under the secret protocol of the German-Soviet Pact).
In June 1941, Slovakia also contributed two motorised infantry divisions to the Axis invasion of the U.S.S.R.