.TTX is a Trados bilingual file format. Phrase will only import those segments from a .TTX file that have been pre-segmented in Trados.
Importing .TTX files into a project is not recommended. These formats are proprietary and are best translated by SDL software. There may be minor or even major incompatibilities when translating Trados bilingual files in non-Trados software.
Features such as pseudo-translation checks are also lost when translating .TTX files.
If there is a trados.ini file attached, ensure it is in the same directory as the .TTX file during pre-segmentation.
Source and target language codes of the .TTX file must match exactly with the language codes the project. If the .TTX file has en-US as a target language, English-United States must be selected for the project target language and not English. If not exact, Trados Studio may not process the file correctly.
Segments imported as Confirmed are saved to the project translation memory in Write mode.