Real world example of this is I just completed the last tier of that assault battle where you can use First Order against the Jedi.
I sent in SLKR, KRU, DVRey, Sith Trooper and OGKylo. I won the event, however, to get there I had to sit through about 20minutes of endless enemy turns.
Skill issue.
Hux prevents TM gain. If you had put in Hux instead of OGKylo, the enemy team couldn't TM-Jump and you wouldn't have had to sit through that.
One of the single most important skills a player can have in this game is knowing what you have available to stop TM gain -- or to frustrate it.
JML can stop 1 key toon from gaining TM. If that toon is key to the TM train, that might be enough.
Admiral Raddus stops TM gain by Empire.
Lord Vader has AoE Daze.
JMK negates all TM gain in his leadership.
Hux negates ENEMY TM gain, but not allied TM gain, if he has advantage, which, if you're using SLKR and a tank, he will. This is perhaps the best TM-jumping negation ability in the game.
PKHO has TM jumping himself, which, combined with Captain Silvo, makes it easy to get out ahead of enemies and take out one or even 2 enemies that provide TM gain before they even move -- do to them what they threaten to do to you.
Tuskens gain infinite Defense and infinite Tenacity when the enemy TM-jumps. The other side does go, and you can wait for a one minute, but not for 20. It doesn't take long before they are all stunned (attacking a Tusken with 15+ stacks of Momentum results in them stunning themselves), then you go again.
There are so many ways to handle TM jumping. If you don't like it, just take some time to learn about the tools you have available to you. Hux is the obvious one in this case bc you need to use First Order in that battle, but you have so many different mechanisms available that this shouldn't be hard.