That's strange. I took Quamper's circle problem froze the 0 layer using your function and attempted to increase the size of all the radii by 1. ACAD acted like it performed the function, but didn't. However, using your function again to thaw everything, the circles don't show up. If I use the same ssget function that selected them when they were frozen to collect them again, they are selected and in the database, but regen won't force them to show up. On that thought, I checked for flipped bit flags and tested them again, changing dxf code 67 from 0 to... 0 and they appeared. No idea why, but I did learn that I can't alter an object that is frozen, even through the back door.
Here's the code I used for changing the radii:
(setq ss (ssget "x" (list (cons 0 "CIRCLE"))))
(setq cnt (1- (sslength ss)))
(while (> cnt -1)
(setq ename (ssname ss cnt))
cnt (1- cnt)
elist (entget ename)
alter (subst (1+ (cdr (assoc 40 elist))) (assoc 40 elist) elist))
(entmod alter)
(entupd ename)
)