I think you mean in some cases, leaks did not correlate with excess heat.
No, that never happened with Miles, or anyone else as far as I know. There are no reported cases of excess helium without corresponding excess heat. There were no leaks at all; only permeation. As I said, leaks would produce hundreds to thousands of times higher levels of helium.
There were no leaks or permeation not correlated with excess heat, but in one case there was apparent excess heat not correlated with helium. That was probably false excess heat. See p. 19:
"Our only gas sample in nine experiments that showed excess power, but no detectable helium, was sample 12/17/90-B (References 14 through 16). Eight days later at the end of this experiment, the D2O level in cell B was 5.1 mL lower than in its companion cell A. An unusual voltage increase with time was observed the previous day (12/16/90) for cell B but not for cell A, suggesting that the D2O level was already much lower than normal and was not completely covering the electrodes in cell B. We later demonstrated that the low D2O level observed in cell B could yield a false excess heat effect. . . .