Can confirm. My world generated the end in 1.9.4 on realms. Initially killed the dragon in 1.9.4 then went to respawn the dragon in 1.10 and it would not work. downloaded a backup to local and tried and it still would not respawn, after reading this bug went into creative locally and lowered bedrock on the edge of exit portal and tried repawning. This worked but upon killing the dragon a new end city gateway did not appear which was the reason for doing this in the first place as I found 4 end cities all without ships and wanted to try a different area.
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Can confirm.
My world generated the end in 1.9.4 on realms. Initially killed the dragon in 1.9.4 then went to respawn the dragon in 1.10 and it would not work. downloaded a backup to local and tried and it still would not respawn, after reading this bug went into creative locally and lowered bedrock on the edge of exit portal and tried repawning. This worked but upon killing the dragon a new end city gateway did not appear which was the reason for doing this in the first place as I found 4 end cities all without ships and wanted to try a different area.