The following features in PowerPoint are not supported:
General
It is recommended to close the PowerPoint template before “local” merging.
Leaving the template open in PowerPoint during a “local” merge operation can sometimes produce unusual results in the output file.
RichText and Image fields when using dot notation or formal style merge fields:
Field types do not produce the desired result if the style of merge field is like the following example:{{HTML:QueryName.FieldName}} or {{Image:QueryName.FieldName}}