timeline preview and export quality is poor compared to asset preview

[PsychicWarrior]

GNU/Linux Slackware 14.1 32 Bit
Openshot 1.4.3 installed via slackbuilds.org script
MLT version 0.9.6 FFMpeg 2.6.3 both installed via slackbuilds.org script

This may or may not be a bug, I am not qualified to say and I do not know enough about debugging, sorry. Indeed this may be a MELT problem.

Following posting on the forum, I downgraded MELT to 0.9.2 and this particular problem (see below) was not present. I switched back to 0.9.6 and even to 0.9.8 and the problem returned.

Sequence of images (1 per frame) imported as a sequence into the asset section of Openshot.

Right click on the asset and select 'preview' and the the sequence plays in the video preview. The quality is as per the imported images (as far as I can tell) and appears ok.

Drag the image sequence from the asset section down onto the timeline.
Press play to output the timeline in the video preview.
The quality of the playback is degraded and so different from the preview of the asset (as detailed above).
If the video is exported, the quality is also poor and looks more or less like it did in the timeline preview, as one would expect.

Selecting a high profile setting makes no difference to the timelibne preview or export quality.

In summary, the asset preview quality is as it should be, the timeline and export quality is worse/poor.

Is this a bug, as one would expect the asset preview and the timeline preview to be the same.
Hope that all makes sense.