Regarding pastic plugs...
From the PDF report on the link in #21, page 10:
Similar to the first experiment, all the plastic clips on each lintel failed, resulting in the cable dropping down. A new observation from this experiment was that the supports in the centre of Lintel 2 had dropped out of the lintel. This was not a failure of the support but rather a failure of the plastic plugs used for fixing the supports to the lintel.
Page 12:
The findings from the short fixings study show that combustible wall plugs in concrete substrates demonstrate signs of weakening of mechanical strength from 300°C and above and that these fixings can fail at 400°C after up to a one hour exposure in controlled conditions.
View attachment 45186
Of course, I'm just picking and choosing bits of the report, it's a bit lengthy but gives a fuller picture.