Hello Mikolaj,
Referring to your observation that the upgrade fixlet is greyed out, note that every fixlet contains a set of conditions (so-called relevances), which determine if/when a particular fixlet can be run.
Relevances usually check if prerequisites (OS type, patches, database level, disks space, etc.) are met or if there are any interfering processes running.
If you find any fixlet as not relevant, then you need to check which condition is not met - see:
https://www.ibm.com/support/knowledgecenter/en/SS8JFY_9.2.0/com.ibm.lmt.doc/Inventory/probdet/t_checking_fixlet_relevance.html
Regards,
MZ
#SupportMigration#AIX#Support