You can watch the OVA at Gundam.info official website for limited time from August 21, 2016.
"The Try Fighters team have been invited to the Nielsen Labs on a tropical island, as test pilots for Yajima Trading's new battle system. However, due to bugs in the new system, they find themselves on standby at the lodging facilities.
As they wait expectantly at the resort-like lodging facilities, Sekai and the others encounter the trio of Shia, Minato, and Gyanko, who have also been invited as test pilots. And a puzzling mystery awaits the rivals who have been reunited on the tropical island...
Now the Try Fighters face their biggest challenge!" [GUNDAM.INFO]
Official GBF Twitter account had also announced back in April 2015 that they will be doing several OVA project for the series.
The upcoming GunPlas from the series was also teased at Shizuoka Hobby show, and they already look promising in terms of design.
Teaser poster from Shizuoka Hobby show teases a Gundam Build Fighters TRY poster with the release month of the series.
Gundam ACE magazine scans via zsurusai.