They actually deliberately dropped the cloakfields as they were escorting the HVT out, since they needed to cover her effectively, and if they cloaked themselves, everyone would've focused their fire on what they saw as an unarmed slave who was suddenly walking around the base as if she owned the place. Decloaking meant that there would be five humans with rifles trained upon them to escort the HVT, thus prompting everyone else to focus their fire on them as opposed to the HVT...
No no it happened before they got to asari in repair shop. Here is the relevant part:
Glancing around the place, Shigure motioned for them all to leave, only for fate to play on them a rather cruel and unusual practical joke on them, to say the least, when what seemed to be the alien's equivalent to a wrench got dropped down from above, a fairly common occurrence in such a workplace, but as fate would have it, the metal tool struck Javelin in the head, the helmet she wore and her shields taking the brunt of the impact and leaving the foot-long piece of metal to ping harmlessly onto the ground below, but it also had the rather unpleasant side effect of causing her cloaking field to collapse, effectively blowing their cover to smithereens.
Silence.
Fubuki, finding that with Javelin's cloak gone essentially meant that their cover was now compromised, had decided to take the initiative before the enemy could, decloaking in an instant with her rifle raised before firing off three quick shots in rapid succession, nailing two aliens and painting the vehicles they were working on in alien gore and causing a tower of stacked crates to fall over, crushing at least two more. Erin and Shepard joined the fights moments later with battle rifles raised and ready, a pair of 7.62x64mm rounds sending another alien off to meet his gods early as well as piercing a neat little hole in a fuel tank on the far end of the place, sending leaking pressurized hydrogen from the tank spraying out in a mist that ignited itself on the .300 Arisaka round's TBX filler, engulfing the far end of the place in flames from the hydrogen igniting. Shigure decloaked shortly afterwards, joining the fray as she fired off a burst of 7.62x40m rounds from her own assault rifle, nailing another technician on the head and painting the vehicle he was working on gore. Javelin decloaked herself moments later, readying her sniper rifle and lining up a shot before pulling the trigger, sending a 14.5x115mm round across the place at hypersonic speeds into the center mass of another mechanic and turned him into a gory mist.
If you check it you will see that Javelin drops ger cloack twice. Once by getting hit with a falling wrench and once by dropping it.
also I do hope you got better with overly large repiting descriptions