Increase Reflection Capture Resoution for Mobile? (can't get higher than 64...)

Hello!

I am trying to increase Reflection Map Resolution of Skylights and/or Spherical Reflections Actors on Mobile (ES3.1)
Not matter what I try, I can’t get them higher than 64. If I switch between ES3.1 and SM5, the reflections at resolution of 64 look absolutely identical.

If I go lower to 32 or 16, both previews show also the correct results.

But if go higher to 128 or 256, the ES3.1 preview wont inrease and still looks exactly like 64.

Am I doing something wrong or is this a limitation of mobile rendering? (which would be REALLY low at 64…)

Cheers
Felix