The Automated Valuation Model (AVM) uses several sub-models to calculate an estimate of the property. While one would expect that the estimate would increase after the property attributes are updated e.g. increasing the core attributes such as bed, bath, car etc. it may not always be the case during the next calculation, which occurs on a weekly basis.
Each sub-model will calculate an estimate and each has its own weighting/influence on the overall estimate which varies for each property. As an example more data that is used by the models has appeared e.g. recent sales/listings that are less favourable in the market, or the update to the target property has changed the pool of comparable properties that are available to the model.
We encourage you to continue to review the estimate of the property, given it is calculated on a weekly basis.