EU wants immigrants in the east, against the wishes of easterners and immigrants both
There are hundreds of thousands of people in Iraq, Syria, Afghanistan, Libya, Somalia, Albania and so on who wish to relocate to Germany and other western EU states.
The German chancellor initially invited them to come, but then realized she would rather not have so many.
OK, so you have numerous potential immigrants who want to go to western Europe, and then you have western Europe which is not really sure whether it wants them or not. Sounds like a straightforward issue between Western Euopeans and the would-be immigrants. Something that needs not involve anyone else.
But you're wrong. Merkel and other EU leaders devised a system where migrants who are granted asylum are then dispersed through the entire EU. Thus Eastern European countries are supposed to take in "their share" albeit that's not where the migrants/refugees are headed, nor did the Easterners ever invite them in.
Why exactly should Eastern Europe share the burden of Western Europe's immigration crisis?
Because of EU solidarity?
EU solidarity did not prevent the Western EU from inventing agricultural quotas to "protect" itself from cheaper Polish grain and Bulgarian tomatoes grown by substantially poorer farmers in the east. Seems it is only fair that the East should likewise think of its own interests first, and let the West deal with this one on its own.
Poland, Czechia and Hungary certainly think so. They've refused to resettle "their share" of immigrants (who don't want to go to Poland anyway). They are now being sued by the EU Commission on Migration, but they claim they will remain defiant:
"From the political point of view, this action ... unnecessarily heats up political tensions, of which there are already too many in the European Union," Polish Deputy Foreign Minister Konrad Szymanski told state TV on Tuesday. He also called the 2015 plan “erroneous,” and argued that Warsaw contributes to solving the migrant crisis by “engaging in protection of EU’s external borders and systematically strengthening its humanitarian involvement in the region.”
"If necessary, Poland is ready to defend its legal arguments in court" he concluded.
"The Czech Republic does not agree with the system of relocation," Prime Minister Bohuslav Sobotka said in response calling Brussels' plan to deal with migrants “dysfunctional.”
"With regard to the worsened security situation in Europe and dysfunctionality of the quota system, it will not participate in it. The European Commission blindly insists on pushing ahead with dysfunctional quotas which decreased citizens’ trust in EU abilities and pushed back working and conceptual solutions to the migration crisis."
In a separate legal battle on the matter, Hungary and Slovakia have challenged the relocation agreement in a top EU court, with an initial indication of the ruling due next month.
Note that as far as the Easterners are concerned the EU can opt not to accept any immigrants, or accept all of them and settle them in the West -- but the one thing they object to is the EU setting their own immigration policy for them.