Saya's vigil - Reinforcement ships takes forever to arrive

[cghawk]

Was doing Saya's vigil ''Find Onko'' where I have to clear the camp and then defeat grineer reinforcements, I thought it was bugged as couple minutes later no enemies arrived but found the problem was the ships moving ridiculously slow when I spotted it in the distance, I waited on the next ship and again it was slow so decided to record it:

 

As can be seen it moves ridiculously slow, only after shooting it does it decide to hurry up but with the 1st ship I must have stood there for almost 5 minutes before the ship arrived.