It seems to me that the missing models are those that were introduced with the update to version 7.3.1:
"Change list Version 7.3.1:
• New models for Ultimate Edition: Blade 700x, CarbonCore 950 Hexa, Dogfighter, Duo Discus, Hexacopter GD-6, Octocopter GD-8,
Fournier RF4-D, Pilatus PC-6 Porter, Goblin 700, Soxos 600, Soxos 700, Soxos 800, Henseleit TDS, Tucan
"