First Kettle Sour - Stuck at 3.8pH

[Zee]

Could I have done this differently to achieve a quicker sour?

60% Pilsner malt
40% Wheat malt
Mashed at 64c
Boiled for 10 mins
1:028
Chilled to 30c
Direct pitch Wyeast Laco Brevis wild sour
Flushed kettle with CO2
Adjusted pH to 4.5 with Lactic Acid
72 hours in it was stuck at 3.8pH OG still stable at 1:028
Gave up, boiled and continued process as normal.

Is something wrong in the process that caused a stuck pH?
Should I have done a laco starter?
Suggestions please

 

[BeerCat]

I cannot advise on kettle souring as i do mixed fermentations but i would recommend this as a good resource Sour beer - Modern Brewhouse wiki
You can make a lacto starter and pitch it after the yeast.

 

[Zee]

I cannot advise on kettle souring as i do mixed fermentations but i would recommend this as a good resource Sour beer - Modern Brewhouse wiki
You can make a lacto starter and pitch it after the yeast.

At this early stage I want to keep bugs away from my brewing stuff as much as possible. Once comfortable I will move to post boil inoculation and aging.

Thanks for the link.