Please set breakpoint in ip_from_search_so to check if it is called and if iv_collection has any entities.
If iv_collection is not called, or iv_collection is INITIAL, maybe the way to transfer data has problem.
I'm not sure in which way to you want to navigate from Z component A to SRQM_INCIDENT_H/MainWindow. You want to navigate to SRQM_INCIDENT_H by clicking something from Z component A? Or just want to embed SRQM_INCIDENT_H as an assignment block of Z component A?
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You have created an IP inbound plug method with importing parameter iv_col, shouldn't be a outbound method called with lv_col from Z component A? You can refer to account search result view BP_HEAD_SEARCH/MainSearchResult->method EH_ONSINGLESELECTION->outbound plug method OP_SINGLESELECTION.
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But since you have added SRQM_INCIDENT_H/MainWindow to component usage, it seems you want to embed it into the Z component overview page? Just like you add Z component B as one assignment block of SRQM_INCIDENT_H, you want to set SRQM_ INDIDENT_H also an assignment block of your Z component A? Is it? If yes, maybe you should also bind context nodes to share data between Z component A and SRQM_INCIDENT_H or get data from entities.