Some units are invisible, and they aren't clickable (with the only way to click on one is using a hotkey)

As I opened up in a skirmish game, I saw that some units were invisible and those that were invisible weren’t clickable and therefore, you couldn’t select them unless you press a hotkey for a certain unit. The animal units were also invisible and also not clickable as well, which made things even worse. The pointed example is pointing at the Explorer unit by the way, which is also invisible.