Troubleshooting

Most surprises have one of a handful of causes. Start with the report: Element details groups every element that was not written by its reason.

"Parameter … not found on category …"

Shown in the Configuration check before the run. The target (or source) parameter does not exist on elements of that category in this model.

The shared or project parameter is not bound to that category in Project Parameters, or — for a family parameter — the family placed there does not have it.
The name differs — check spelling, spaces, and upper and lower case.
Instance and Type are swapped: the field says Instance, but the project has a type parameter of that name, or the other way round.

Nothing was written, and there is no error

Only if empty is ticked for that operation in the Executor, and the elements already have a value. The report lists them as already filled.
The run covers only the Active view or the Selection, and the elements are not in it.
The filter excludes them. Remember that a filter on a parameter value compares upper and lower case exactly.
An Exclusions option in the Executor's settings skips them: groups, assemblies, pinned elements, elements another user holds.

A type parameter keeps its old value

The value came from instances, and the instances of that type in the run did not agree (see Instance and type parameters) — two doors of the same type in different rooms. The type keeps its own value on purpose. Write to an instance parameter instead, or narrow the run so that all instances agree.

"Value does not fit the type"

The operation produced text for a number, length or Yes/No parameter, and Revit refused it: n/a into an integer, maybe into a Yes/No parameter. Use a text parameter as the target, or make the value fit — Calculated Value writes plain numbers.

Map Values finds no row

Text keys are compared exactly, upper and lower case included: iw-100 is not IW-100. Spaces at the start and end are ignored.
With several Look up by parameters, every part of the key must match its own column.
Numbers match with or without the unit, but the unit must be the same: 1 m does not find 1 mm.
The default for no match is Leave unchanged, so a missing row is silent. Set If no row matches to Write text with something visible, such as NOT IN TABLE, while you set up the table.

Room, Space or Area Data writes nothing, or clears values

The element is in no room, and If in no room is empty — which clears the target. Put a text there to see these elements.
The rooms were placed in an earlier phase. Set Room phase to Custom and name it.
The rooms are in a linked model. Room Data reads only rooms of the model it runs in.
The element only partly sits in the room (floor drains, wall-hosted equipment). Turn on Precise detection (slower).
For doors and windows with to room or from room: Revit's To Room and From Room follow the way the door was placed. Try the other side.

A filter selects different elements on another Revit version

Family Name and Type Name filters ignore upper and lower case on Revit 2023 and later, but not on 2021 and 2022. A file that relies on begins with "Basic" should use the exact case so it behaves the same everywhere.

An operation does nothing in one Revit version

The category or built-in parameter it uses does not exist in that Revit — for example a Boundary Conditions category, which only Revit 2027 has, in Revit 2025. The configuration check names it before the run. The Configurator marks such categories with their years — see Categories only some Revit years have.

Pipes and fittings with broken connections

The Executor asks before writing to pipes and fittings Revit already flags as disconnected — see Pipes and fittings with broken connections in the Executor chapter.

"Made with a newer FlexiData"

The file was saved by a newer version than the one opening it. Options this version does not know are ignored, so some operations may not do what the file intends. Update FlexiData on this machine before running it.

Undoing a run

Undo this run in the report takes back everything the run wrote. After the report is closed, the whole run is one entry in Revit's Undo list. A run synchronized with Central cannot be undone.

A reason in the report I do not understand

Every reason the report can give, with what to do about it, is in Report reasons.