The animation for PrimedTnt does not take into account the value of the Fuse, it assumes that it is always 80, the default value. When summoning PrimedTnt with a loarge Fuse value, or artificially increasing the fuse value with command blocks, the PrimedTnt will complete its normal animation after 80 ticks, and then disappear, with the actual explosion from the TNT following.
Environment
[11:11:01 INFO]: Minecraft Launcher 1.6.13 (through bootstrap 5) started on windows...
[11:11:01 INFO]: Current time is Jul 1, 2015 11:11:01 AM
[11:11:01 INFO]: System.getProperty('os.name') == 'Windows 8.1'
[11:11:01 INFO]: System.getProperty('os.version') == '6.3'
[11:11:01 INFO]: System.getProperty('os.arch') == 'amd64'
[11:11:01 INFO]: System.getProperty('java.version') == '1.8.0_31'
[11:11:01 INFO]: System.getProperty('java.vendor') == 'Oracle Corporation'
[11:11:01 INFO]: System.getProperty('sun.arch.data.model') == '64'
duplicate of MC-2490