Seems to be a limitation that exponent notation is only supported if you use a capital āEā. I tried it with 5.605193857299268E-45 and it was parsed correctly. Might be a candidate for a change request / issue in github.
edit: You could apply an incoming value transformation (e ā E) to fix it, e.g. REGEX:s/e/E/g
Thanks @absalom for the explanation and the workaround.
Had the same thought applying a transformation on the channel, but you even provided the regex in your edit, thanks!