fanfare identified the problem. Any portion of a distribution that is reported as rolled over (by an ordinary rollover) is not permitted to be reported as a Coronavirus-Related Distribution.
TurboTax developers apparently did fully not anticipate users making this mistake and ended up with slightly different implementations of Form 8915-E for Taxpayer and of Form 8915-E for Spouse. The implementation for Taxpayer recognizes that none of the distribution is actually a CRD and just treats it as an ordinary rollover but the implementation for Spouse does not entirely do so. For spouse it treats it as a taxable CRD but for the purpose of a repayment treats it as not a CRD and ignores the repayment. This is why switching the recipient changes the behavior.
