From the NDRC report, page 18:
"There are, however, two major limitations to a simple passive photoelectric fuze: (1) since the sun is used as a source of energy, operational use is restricted to daytime, and (2) the sun is also a target in the sense that if the detector of the fuze "sees" the sun directly, malfunction of the fuze may occur.
These two limitations were recognized in the beginning and led to termination of the work only after more difficult designs (radio) had proved practicable for proximity operation.
An infrared fuze would not be subject to the first limitation above but would be affected by the second. For this reason, infrared designs based on rapid, sensitive detectors developed by Division 16, NDRC, were abandoned after brief consideration. The practicability of available radio fuzes was also a major factor in the abandonment."
As there are only so many ways to skin that cat, one might presume the Japanese faced the same problems.