I rarely use SC to attack, so I've never experienced this in PVP. I don't know what can be hapenning, but during some heroic defenses I was unable to deploy my SC troops to defend my base. I click, click, click to deploy and it does nothing. It hapenned not one, or two, but several times, so I stopped request troops or trying to use SC troops only for HDs while I can win the Bronzium Crate only with Armory turrets and GR, maybe one or two heroes.
SWC Windows survivor.
Imperial Prestige / Rebel Prestige on vacation and trying new games.
If you are Rebel join "Solo's_Band" (war squad) or "Ewok_revenge" (training squad)