Delhi sultanate villagers try to garrison into houses if there is no garrisonable building(town center, outpost, or castle) with 12-13 tiles when reinforced foundation, the house of learning technology that allows units to be garrisoned within houses isn’t researched. Delhi is the only civilization that is affected. I hope this screenshot can visualize the problem.
Delhi villagers try to garrison houses without reinforced foundation being researched
Thanks @Gerix55! Should be a fix coming for this one.